Systems and methods for automated fluid response measurement

ABSTRACT

A device is provided for automatically assessing functional hemodynamic properties of a patient is provided, the device comprising: a housing; an ultrasound unit coupled to the housing and adapted for adducing ultrasonic waves into the patient at a vessel; a detector adapted to sense signals obtained as a result of adducing ultrasonic waves into the patient at the vessel and to record the; and a processor adapted for receiving the recorded signals as data and transforming the data for output at an interface. Other devices, systems, methods, and/or computer-readable media may be provided in relation to assessing functional hemodynamics of a patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/619,202 filed Jun. 9, 2017, which is continuation-in-part ofPCT Application No. PCT/CA2016/051451, entitled “SYSTEMS AND METHODS FORAUTOMATED FLUID RESPONSE MEASUREMENT”, filed 9 Dec. 2016, the PCTApplication claiming priority to U.S. Application No. 62/265,682,entitled “SYSTEMS AND METHODS FOR AUTOMATED FLUID RESPONSE MEASUREMENT”filed 10 Dec. 2015.d

TECHNICAL FIELD

The present disclosure generally relates to the field of monitoringbiological signals, and more particularly, hemodynamic monitoring ofpatients.

BACKGROUND

Innovative, affordable, and/or portable non-invasive hemodynamicmonitoring devices may be desirable in the market. Such devices, forexample, aid in the provisioning of care of various individuals, (e.g.,the critically-ill) by providing functional hemodynamic assessments(which, in some embodiments, may be instantaneous or nearinstantaneous).

Non-invasiveness of monitoring/measurement is of importance asnon-invasive devices do not require consideration of potentialcomplications that would otherwise arise in conjunction with invasiveinterventions. For example, an invasive intervention could lead toinfection, require additional surgical steps to be taken (which may notbe possible when time is of the essence), require time forhealing/tissue repair, among others. Further, non-invasive approaches,in the context of emergency situations, would have less requirements forsterilization, specialized skillsets and equipment.

The portability of a monitoring/measurement device is very desirable asthe device may be transported to areas where it may be used (as opposedto having to have patients transported to come to where the device islocated). However, portability implies that the device may need to besufficiently small (not bulky), and light for ease of transportation,and further, may constrain available power delivery to the device due toa need for portability of power sources.

It is desirable to be able to assess functional hemodynamics in avariety of circumstances. Unstructured environments and the variance inexperience and training among individuals responsible for assessingfunctional hemodynamics creates challenges. These challenges areexacerbated when a patient requires monitoring over a protracted periodof time and many individuals are involved in assessing functionalhemodynamics. There is a need for a device that will produce precise andrepeatable measurements under these conditions.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect, a portable non-invasive hemodynamicmonitoring device is provided, the device including a housing configuredfor removable coupling to a body part of an individual, the body partincluding at least one vessel of interest; an ultrasound unit coupled tothe housing and adapted for adducing ultrasonic waves into the at leastone vessel of interest in a continuous beam, the ultrasound unitincluding: a plurality of transducer pairs adapted to continuouslydetect reflected overlapping ultrasonic waves derived at least in partfrom the produced ultrasonic waves directed to intercept at least onevessel of interest and oriented such that, in concert, the plurality oftransducer pairs producing the overlapping ultrasonic waves at an angleof incidence between about 25 degrees to about 60 degrees in respect ofa plane of fluid flow through the at least one vessel of interest; aprocessor configured to continuously extract hemodynamic parameters fromone or more characteristics of the detected reflected ultrasonic wavesin real-time or near real-time by applying a signal processing routine,and to store the extracted one or more hemodynamic parameters in a datastorage; and a sensory output device adapted to provide feedback basedat least on the extracted hemodynamic parameters, the sensory outputdevice including at least one of (i) a graphical display and (ii) anauditory display; the orientation of plurality of transducer pairsmaintained by the housing such that the plurality of transducer pairsare oriented to adduce the overlapping ultrasonic waves at substantiallysimilar angles in respect of the plane of fluid flow through the atleast one vessel of interest, the plurality of transducer pairs, inconcert, adducing an ultrasonic curtain focused in the curtain thicknessdimension comprised of the overlapping ultrasonic waves that enables aplurality of redundant effective placement positions offeringnon-critical physical placement of the portable non-invasive hemodynamicmonitoring device.

In accordance with an aspect, there is provided a portable non-invasivehemodynamic monitoring device comprising a housing configured forremovable coupling to a body part of an individual, the body partincluding at least one vessel of interest; an ultrasound unit coupled tothe housing and adapted for adducing ultrasonic waves into the at leastone vessel of interest in a continuous beam, the ultrasound unitincluding: at least one transducer pair adapted to continuously detectreflected overlapping ultrasonic waves derived at least in part from theproduced ultrasonic waves directed at the at least one vessel ofinterest and oriented such that, in concert, the at least one transducerpair produces the overlapping ultrasonic waves at an angle of incidencebetween about 25 degrees to about 60 degrees in respect of a plane offluid flow through the at least one vessel of interest; a processor.

In accordance with another aspect, the processor is further configuredto continuously extract hemodynamic parameters from one or morecharacteristics of the detected reflected ultrasonic waves in real-timeor near real-time by applying a signal processing routine, and to storethe extracted one or more hemodynamic parameters in a storage.

In accordance with another aspect, there is provided a sensory outputdevice adapted to provide feedback on a quality of the extractedhemodynamic parameters, the sensory output device including at least oneof (i) a graphical display and (ii) an auditory display. Wherein theorientation of the at least one transducer pair improves a probabilityof proper acoustic coupling between the ultrasound unit and the bodypart of the individual by enabling a plurality of redundant effectivenon-critical placement options of the housing on the body part of theindividual, the plurality of redundant effective placement optionsreducing a required precision of placement of the device.

In accordance with another aspect, the signal processing routineincludes processing the reflected ultrasonic waves according to acontinuous wave Doppler ultrasound process.

In accordance with another aspect, the at least one transducer paircomprises a chain of transducer pairs.

In accordance with another aspect, the at least one transducer pair isat least one flexible polymer based transducer pair.

In accordance with another aspect, the at least one transducer pair isoriented in a saw tooth pattern, the saw tooth pattern causing theoverlapping ultrasonic waves to be produced at the angle of incidencebetween about 25 degrees to about 60 degrees in respect of a plane offluid flow through the at least one vessel of interest.

In accordance with another aspect, the housing includes a tensionbandage that is utilized to provide the removable coupling between thehousing and the body part of the individual, the tension bandage beingtensioned such that a sufficient downward force is applied to theultrasound unit.

In accordance with another aspect, the tension bandage is configured tomaintain a substantially constant angle of incidence of the adducedultrasonic waves relative to the at least one vessel of interest inorder to enhance consistency of repeat measurements over a duration oftime.

In accordance with another aspect, the sensory output device isconfigured to generate a sensory output indicating an effectiveness ofplacement of the ultrasound unit.

In accordance with another aspect, processor is further configured todetect an estimated return of spontaneous circulation (ROSC) event bymeasuring a difference between a first relative blood flow from a chestcompression and a second relative blood flow from a heartbeat, and thesensory output device is configured to generate a sensory outputindicating the occurrence of the detected estimated return ofspontaneous circulation (ROSC) event and indicating that any chestcompression activities should cease.

In accordance with another aspect, the housing includes at least onedata communication device operable to transmit the extracted hemodynamicparameters from one or more characteristics of the detected reflectedultrasonic waves over a data network.

In accordance with another aspect, the data communication devicetransmits the extracted hemodynamic parameters from one or morecharacteristics of the detected reflected ultrasonic waves over the datanetwork to an external computer system.

In accordance with another aspect, the housing includes at least onedata transfer bus operable to transmit the extracted hemodynamicparameters from one or more characteristics of the detected reflectedultrasonic waves over a data connection.

In accordance with another aspect, the data transfer bus is operable totransmit the extracted hemodynamic parameters from one or morecharacteristics of the detected reflected ultrasonic waves over the dataconnection to one or more external connected devices.

In accordance with another aspect, the hemodynamic parameters include atleast one of: a peak velocity of a Doppler shift detected in the atleast one vessel of interest; a velocity-time integral of signal changesbetween heartbeats; and a ratio measured between a post-interventionvelocity-time integral and a pre-intervention velocity-time integral.

In accordance with another aspect, the frequency of the ultrasonic wavesis a frequency between about 3 MHz to about 12 MHz.

In accordance with another aspect, the frequency of the ultrasonic wavesis a frequency is about 4 MHz.

In accordance with another aspect, the processor is configured todetermine whether the individual is undergoing compensated shock by:continuously monitoring a ratio between a heart rate and a velocity-timeintegral of fluid flow through the at least one vessel of interest;entering a compensated shock alarm state when the ratio exceeds apre-defined threshold; and producing an alarm signal when thecompensated shock alarm state is entered.

In accordance with another aspect, the sensory output device isconfigured to transmit a signal when the processor determines that theindividual is undergoing compensated shock.

In accordance with another aspect, the processor is further configuredto: extract at least one first feature of interest from one or morecharacteristics of the detected reflected ultrasonic waves prior to anintervention event; extract at least one second feature of interest fromone or more characteristics of the detected reflected ultrasonic wavessubsequent to the intervention event; determine at least onepost-intervention change value equivalent to the difference between theat least one first feature of interest and the at least one secondfeature of interest.

In accordance with another aspect, the intervention event is theadministering of at least one medicament.

In accordance with another aspect, there is provided a device adaptedfor automatically assessing functional hemodynamics of a patient, thedevice comprising: a housing; an ultrasound unit coupled to the housingand adapted for adducing ultrasonic waves into the patient at a bloodvessel; a detector adapted to sense signals obtained as a result ofadducing ultrasonic waves into the patient at the blood vessel and torecord the signals in the form of raw data; and a processor adapted forreceiving the raw data and transforming the data for output at aninterface.

In accordance with another aspect, the processor is further adapted tomonitor functional hemodynamics (e.g., fluid dynamics) when the patientundertakes a fluid challenge activity.

In accordance with another aspect, the processor is further adapted tomonitor functional hemodynamics both before and after the patientundertakes a fluid challenge activity.

In accordance with another aspect, the processor is further adapted tocompare the data before the patient undertakes a fluid challengeactivity and after the patient undertakes a fluid challenge activity todetermine a change in velocity time integral of blood flow in the bloodvessel.

In accordance with another aspect, the change in velocity time integralof blood flow in the blood vessel is tracked as a ratio of the velocitytime integral before and following an intervention.

In accordance with another aspect, the processor is further adapted toprovide the ratio and a notification for a clinician if the ratio is atleast one of: 10% or greater, 15% or greater, or 20% or greater.

In accordance with another aspect, the ultrasound unit is provided as anultrasonic probe separate from the housing and coupled operatively tothe housing.

In accordance with another aspect, the device is provided in the form ofa portable ultrasound unit.

In accordance with another aspect, the device is provided in the form ofa cart mounted ultrasound unit, for example, a function specifictransducer integrated into a cart/portable ultrasound can be provided insome embodiments.

In accordance with another aspect, the device is incorporated into ahand held ultrasound device.

In accordance with another aspect, the ultrasound unit is integratedinto the housing.

In accordance with another aspect, the processor is adapted to performthe automated detection of blood flow in the blood vessel, the processorreceiving the raw data from adducing the ultrasonic waves (e.g., in acontinuous beam or a pulsed beam) into the patient at an angle opposingthe blood flow in the blood vessel, obtaining a velocity time trace inrelation to the blood flow, determining a velocity time integral,determining a cross-sectional surface area of the blood vessel, andutilizing the velocity time integral and the cross-sectional surfacearea of the blood vessel to establish the blood flow through the vesselacross a period of time.

In accordance with another aspect, the processor is adapted to perform avalidation protocol for identifying an optimal set of parameters foroperation of the device.

In accordance with another aspect, the optimal set of parametersincludes at least one of placement position, fixation type, selection oftransducer pairs (e.g., one, some, or all) patch placement, and angle ofincidence. In various further aspects, the disclosure providescorresponding systems and devices, and logic structures such asmachine-executable coded instruction sets for implementing such systems,devices, and methods.

In this respect, before explaining at least one embodiment in detail, itis to be understood that the embodiments are not limited in applicationto the details of construction and to the arrangements of the componentsset forth in the following description or illustrated in the drawings.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

In various further aspects, the disclosure provides correspondingsystems and devices, and logic structures such as machine-executablecoded instruction sets for implementing such systems, devices, andmethods.

In this respect, before explaining at least one embodiment in detail, itis to be understood that the embodiments are not limited in applicationto the details of construction and to the arrangements of the componentsset forth in the following description or illustrated in the drawings.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

Many further features and combinations thereof concerning embodimentsdescribed herein will appear to those skilled in the art following areading of the instant disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures, embodiments are illustrated by way of example. It is tobe expressly understood that the description and figures are only forthe purpose of illustration and as an aid to understanding.

Embodiments will now be described, by way of example only, withreference to the attached figures, wherein in the figures:

FIG. 1 is a perspective view of a device placed on the neck of apatient, according to some embodiments.

FIG. 2 is illustrative of a conventional ultrasound unit, the GE VScan™having a display, and a probe.

FIG. 3 is an illustration of an example neck profile, according to someembodiments.

FIG. 4 is a depiction of a common carotid artery (CCA) Flow MeasurementAngle, according to some embodiments.

FIG. 5 is an illustration of an example tensioning mechanism formaintaining acoustic coupling between the device and a body partaccording to some embodiments.

FIG. 6 is an example block schematic diagram of a device, according tosome embodiments.

FIGS. 7A and 7B illustrative of some example components that may beutilized for interfacing with a patient's body, according to someembodiments.

FIG. 8 depicts an example adhesive by 3M™.

FIGS. 9A-9C illustrate a pocket-size embodiment; FIG. 9A provides a topelevation view, FIG. 9B provides a perspective view, and FIG. 9Cprovides a side cross-sectional view, according to some embodiments.

FIG. 10 is an illustration of a pocket sized embodiment.

FIGS. 11A-11C are illustrative of a small embodiment with a coupledprobe, according to some embodiments. FIG. 11A is a front perspectiveview of the embodiment; FIG. 11B is a rear perspective view of theembodiment; and FIG. 11C is a partial view of the embodiment.

FIGS. 12A and 12B and FIGS. 13A-13C are illustrative of a smallembodiment with integrated probe, according to some embodiments. FIG.12A is a side view of this embodiment, and FIG. 12B is a perspectiveview of this embodiment. FIG. 13A is a perspective view of a secondversion of the embodiment with integrated probe being held at a handle.FIG. 13B is a perspective view of the second version; and FIG. 13C is aside view.

A cart embodiment is provided at FIGS. 14A and 14B; FIG. 14A is a frontperspective view of a cart embodiment, and FIG. 14B is a side elevationview of the cart embodiment.

FIG. 15 is a flow diagram displaying the typical stages of medical carea patient may undergo in the event of critical illness.

FIG. 16 is a cross-sectional diagram of a device according to someembodiments.

FIG. 17 is a top view diagram of a device according to some embodiments.

FIG. 18 is a cross-sectional diagram of a device displaying the “sawtooth” configuring of the transducer-receiver pair and its orientationrelative to blood vessels, according to some embodiments.

FIG. 19 is a top view diagram of an ultrasound sensor and itsorientation relative to blood vessels, according to some embodiments.

FIG. 20 illustrates an example surface profile of a matchstick element,according to some embodiments.

FIGS. 21A and 21B are “heat map” plots of the ultrasonic signalsgenerated by the matchstick transducers, according to some embodiments.

FIG. 21C is a more detailed version of FIG. 21B, showing the beam“wedge” in greater detail.

FIG. 22 illustrates two matchstick elements and a blood vessel ofinterest, according to some embodiments.

FIG. 23 illustrates a series of matchstick transducer pairs, accordingto some embodiments.

FIG. 24 is a perspective rendering of a device, according to someembodiments.

FIG. 25 is an illustrating indicating an approach to obtainingmeasurements and signals using a typical handheld device.

FIGS. 26 and 27 are illustrations of a device providing an unfocusedcurtain is provided, according to some embodiments.

FIG. 28 illustrates a set of matchstick transducers, according to someembodiments.

FIG. 29 is an illustrative graph of blood signal level as compared todepth, according to some embodiments.

FIG. 30 is a graph illustrating received signal input level, in blood,showing dB volts plotted against depth, in centimeters.

FIG. 31 illustrates is an isometric view of a number of transducerelements in accordance with one embodiment of the disclosed technology.

FIGS. 32 and 33 are block diagrams of a number of signal processingcomponents in an ultrasound patch in accordance with one embodiment ofthe disclosed technology.

FIGS. 34A-44 are a series of computer illustrations showing theconstruction of an ultrasound patch in accordance with one embodiment ofthe disclosed technology.

FIGS. 34A and 34B show a pair of ultrasound transducer elements in ablock of backing material in accordance with one embodiment of thedisclosed technology.

FIGS. 34C, 34D, 34E and 34F show views of a block of backing materialfor supporting a pair of ultrasound transducer elements in accordancewith one embodiment of the disclosed technology.

FIGS. 35A and 35B show electrical connections to transducer elements inaccordance with one embodiment of the disclosed technology.

FIGS. 35C and 35D show transducers on a flex circuit in accordance withan embodiment of the disclosed technology.

FIG. 36 shows a number of transducer pairs on a flex circuit inaccordance with one embodiment of the disclosed technology.

FIG. 37 shows a battery below a flex circuit in accordance with oneembodiment of the disclosed technology.

FIG. 38 shows a printed circuit board below a battery in accordance withone embodiment of the disclosed technology.

FIG. 39 shows a rigid chassis below an ultrasound transducer inaccordance with one embodiment of the disclosed technology.

FIG. 40 shows a number of flexible polyurethane pads below a number oftransducer elements in accordance with one embodiment of the disclosedtechnology.

FIG. 41 shows an over mold for an ultrasound transducer in accordancewith one embodiment of the disclosed technology.

FIG. 42 shows an adhesive bandage on an ultrasound transducer inaccordance with one embodiment of the disclosed technology.

FIG. 43 shows a hydrogel insert on an ultrasound transducer inaccordance with one embodiment of the disclosed technology.

FIG. 44 shows a plastic shell for an ultrasound transducer in accordancewith one embodiment of the disclosed technology.

DETAILED DESCRIPTION

Embodiments of methods, systems, and apparatus are described throughreference to the drawings.

The following discussion provides many example embodiments of theinventive subject matter. Although each embodiment represents a singlecombination of inventive elements, the inventive subject matter isconsidered to include all possible combinations of the disclosedelements. Thus, if one embodiment comprises elements A, B, and C, and asecond embodiment comprises elements B and D, then the inventive subjectmatter is also considered to include other remaining combinations of A,B, C, or D, even if not explicitly disclosed.

Innovative, affordable, and/or portable non-invasive hemodynamicmonitoring devices are desirable. Such devices, for example, aid in theprovisioning of care of various individuals, (e.g., the critically-ill)by providing functional hemodynamic assessments (which, in someembodiments, may be instantaneous or near instantaneous).

There may be, however, various technical challenges in providing such adevice, such as ensuring that readings are accurate, specific, andreliable within a tolerable performance range (e.g., accounting for thepresence of noise, accounting for transient signals and/or aberrations);accounting for variations in physical dimensions and/or deviceplacement, contact, and environment (e.g., differing neck sizes,contours, proximity of device, signal transfer characteristics);accounting for variations in procedures performed in conjunction withthe device (e.g., differing fluid challenges).

Further, the device may benefit from a level of user-independentmeasurement repeatability, such that a patient, for whom manycare-providers will be responsible, can monitor functional hemodynamicsaccurately over a protracted period of time. It may be desirable forsuch a device to contain access to memory and log sensor data over saidprotracted period of time.

A robust measurement device may be desirable, such that the device canprovide real-time feedback during, for example, chest compressionsassociated with cardiopulmonary resuscitation (CPR), among otheroperations where comparing pre-/post-intervention measurements may alsobe desirable. Further still, it may be desirable to provide a devicethat adheres to the patient such that the care-provider's hands may befreed to perform other critical functions.

A device including an flexible ultrasound transducer is provided in someembodiments, the ultrasound transducer including aligned transducerpair(s) that are used to produce a sheet of ultrasound that can sampleheterogeneous tissue (e.g., muscle, vessels, blood) to quantify forwardand reverse blood flow. The device is non-invasive and is able toperform biological measurements without the need for insertion of othercomponents (e.g., catheters). The non-invasive aspect is important insome embodiments as non-invasive approaches have a substantially lowerrisk of infection, do not require recovery time, and are more readilyadapted for use by less skilled caregivers.

The transducer can be incorporated into a system for automatic flowmonitoring and functional assessment without or with minimal user inputaccording to various embodiments. An example system may be a one-timeuse disposable portable ultrasound system that includes a tensionbandage for secure coupling, that provides a cost-effective tool for usein an emergency. The ultrasound system may be battery operated andconfigured for wireless communications (e.g., by cellular, WiFi,Bluetooth™). The system may have audio and graphic outputs included onthe bandage, and in some embodiments, further signal processing isperformed on an external device, such as a laptop, tablet or smartphone. Additional analytics may be mounted, such as componentsconfigured for determining hydration level.

The disclosed ultrasound transducer (also referred to an ultrasoundbandage) is designed for functioning without the user having to landmarkand/or focus the ultrasound transducer on the vessel of interest, forexample. by having wide array of continuous wave ultrasound transducersas described in various embodiments. An unfocused curtain of ultrasonicsignals generated from an array of non-coplanar elements (e.g.,transducers all having the same fixed angle, which angle may varyslightly due to device confirming to anatomy, or a matrix of fixed angletransducers) is provided such that redundant placement options arepossible. For example, a plurality of transducers may be provided, and ahighest signal-to-noise ratio pair may be selected. The device isdeveloped to be relatively insensitive to placement on the patient(providing multiple placement and orientation options), so that it isquick and easy to deploy (e.g., many situations need extremedeploy-ability and ease of use, such as emergency and battlefieldsituations). Accordingly, reproducible measures (e.g., robust repeatsampling, reduced angle variability) and constant transducer angles areprovided by design, rather than reliant on the user's skill level.

Some disclosed embodiments are designed for hands-free usage, forexample, a single operator in an intensive care unit may wish to utilizehis/her hands for other functions. Other intervention may be effectedwhile the device is in use, and ease of use and flexibility inapplication/placement is important as emergency caregivers may need tohave their hands free to be able to administer other interventions(e.g., fluid bolus therapy). The device of some embodiments isconfigured to track measurements pre- and post-intervention to track theefficacy of such intervention, using the fluid measurements as proxy forpredicted efficacy (e.g., does there appear to be clinicalimprovement?).

The ultrasound bandage of the disclosed technology is adapted forpractical usage in emergency situations where speed of use and placementare critical in delivering care. Conventional imaging ultrasound, whileadapted for accuracy, typically require careful placement, goodcoupling, and use bulky diagnostic devices (for example, use alongsideinvasive diagnostic equipment, ECGs). Where careful placement isrequired, ultrasound system adjustments are typically needed. Further,where multiple ultrasonic transducers are utilized in conventionalapproaches, the multiple ultrasonic transducers are required to havebeam intersection, presumably to aid in improving accuracy throughmechanical focusing of beams. Rather than focusing a plurality of beams,some embodiments of the disclosed technology are configured to captureall or substantially all signals moving towards or away from thetransducers in a large swath of tissue.

For example, some conventional approaches include the use of adhesivemembers with reference indicia for correct placement relative toanatomical landmarks, or complicated mechanisms where, for example, aplurality of transducer beams are required to intersect, among others.Such conventional approaches are not feasible or practical in thecontext of emergency care. Time is of the essence, and the ability toquickly deploy and obtain readings allows a primary caregiver a betterchance of success.

By immobilizing (via an adhesive patch with an acoustic coupler on theneck) the transducer sets in a saw tooth orientation on an adhesivepatch, a preferred embodiment is configured to enhance thereproducibility and comparability between repeat measures before andafter an intervention (e.g., across multiple distinct events to extracthemodynamic parameters from the transducer pair(s)). In the preferredembodiment, the transducer sets and the saw tooth orientation are heldto have a same angle of attack (e.g., beam angle) across each of thetransducer sets in respect of a plane of fluid flow. This orientationallows the mechanism to emit signals that penetrate the tissue, andcreates a “continuous unfocused ultrasound curtain-shaped beam” thatprovides for improved ease and flexibility of placement. For example, acaregiver may not necessarily have enough time to accurately determineplacement, and the “continuous unfocused ultrasound curtain” aids inestablishing a redundancy of placement options such that the device orsystem is still operable despite suboptimal placement, providing asignal that is accurate enough for emergency care.

The disclosed system, in some confirmations, is able to monitor bloodflow in two directions.

The ultrasound transducer may be incorporated into an overall system ordevice (e.g., a miniaturized singular device that operates as aone-piece bandage member that can be quickly applied prior to or duringemergency care) that is configured to measure signals before, during,and/or potentially after an intervention, or combinations thereof.Differences in combinations of these signals can be used to identify,for example, the occurrence of events (e.g., return of spontaneouscirculation), to determine characteristics of blood flow over a periodof time (e.g., a velocity-time Integral), and/or to determine theefficacy of emergency intervention (e.g., an indication of feedbackregarding success of CPR).

The device may be a standalone unit (e.g., having on-board displays orother interface elements) whereby auditory and/or visual displays areused to convey information regarding treatment. In other embodiments,the device is operable for use with downstream or external processorswhich receive raw or processed data sets from the device, and generateone or more healthcare insights based on the processing of the datasets. Such processors may be on-board, or on a separate device or in adistributed resources implementation (e.g., a cloud-basedimplementation). Some embodiments may off-load processing to a connectedsmartphone/tablet/computer. In another embodiment, on-board processorsmay be utilized to perform further analysis and signal processing, forexample, noise removal, artifact identification, signal shaping, metricextraction, among others.

FIG. 1 illustrates a device 102 placed on the neck of a patient,according to some embodiments. The device 102 is illustrated havingvarious components and structural aspects, and it should be noted thatthe device 102 is provided merely as an example and embodiments may havedifferent, alternate, the same, more, and/or less components andstructural aspects.

The patients that may use this device 102, may, for example, be older inage and suffering from heart complications. The patients may be weak,may not be in a state of full awareness, and may be in danger of acuteand critical illness. The device 102 may also be suitable for variousother patient types.

Those patients who are alert are often in a stressful state. Thoughefficacy may be a significant factor, keeping the patient calm andcomfortable is also an important factor.

A device 102 that seems to constrict or feel unnatural on the patient,such as a bulky or heavy neck mounted device 102, might serve toincrease patient stress. A smaller device 102, or one with a detachedprobe, may be advantageous in this regard. Further a device 102 that isnon-invasive is particularly desirable from a healthcare riskperspective.

The device 102 shown is configured for providing automated fluidresponse ultrasound (AFRU), and may, for example, be a body mounteddevice 102 that may be configured to incorporate a portable ultrasoundunit to provide one or more assessments of a patient with consistencyand/or accuracy. The device 102 may provide functional hemodynamicassessments. For example the device 102 may determine a patient's fluidresponsiveness (FR), in an automated fashion. In some embodiments, thelocal site on the patient is generally the neck area, such that thecarotid artery is the vessel of interest and carotid flow is the targetmeasurement. In some embodiments, the vessel of interest may be anothervessel (e.g., brachial artery, femoral artery, etc.) and, as a result,the target measurement may change accordingly.

The device 102 may, for example, be used in combination with variousinterventional procedures such as a leg raise, to give live readingsduring a fluid challenge (e.g., passive leg raise), etc. Further, thedisclosed ultrasound bandage is non-intrusive, may be used by untrainedusers, may include methods by which certain target blood vessels areautomatically differentiated from the other blood vessels, etc. Thedevice 102 may, in some embodiments, be used for multiple measurementswhere the device 102 may be fixed in place between measurements. Forexample, in some embodiments in order to differentiate target bloodvessels from other blood vessels, forward and reverse flow signals maybe classified as venous or arterial by application of a flow profile(e.g., pulsatile positive direction against non-pulsatile+opposite ofpositive direction). The transducer beam may be wide enough to capturethe entirety of both arterial and venous signals at a particularmonitored cross-section.

A user interface 110 may be integrated into or operatively paired withthe device and thus the device 102 may not require external supportinghardware. However, the device may, in some embodiments, be integratedwith a data communication device 112, for example using the Bluetooth™or Wi-Fi protocol. The data communication device 112 may be configuredsuch that the device is capable of transmitting outputs to an externalsystem (e.g., an external computer system) for processing, data storage,display, etc. The user interface 110 may be a visual display, a speaker,or another interface capable of communicating messages to a user of thedevice. In some embodiments, the device 102 may contain one or more datatransfer buses operable to provide non-networked data connection meansthat may allow the device 102 to transfer and receive data to and/orfrom external connected devices (e.g., universal serial bus (USB) harddrives, monitors, etc.).

In some embodiments, various disposables may be used with the device102, such as a disposable that integrates a patient interface with anacoustic carrier (e.g., a gel and an adhesive). According to someembodiments, the device may communicate data to a secondary processingsystem via a communications network—the secondary processing system mayprocess received data according to data-analytics models and/or mayintegrate received data with previously stored data.

In FIG. 1, the device 102 is depicted along with a patient's bloodvessels (noted as reference numerals 104, in this example, the carotidand 106). In such an embodiment, the output of the device 102 may beindicative of reflected hypersonic waves transmitted by transpondersforming part of the device 102, and reflecting off of a vessel ofinterest (in this example, the carotid artery). The received reflectedsignals, when processed, may produce an output indicative of hemodynamicproperties of blood flow from the patient's heart 108, through thevessel of interest. The device 102 may output through the user interface110, for example, as various readings that can be interpreted by amachine and/or a healthcare practitioner. The blood flow and/or vesselwalls may be tracked using an ultrasound sensor, and denoted asreflected signals undergoing a Doppler shift. The measured Doppler shiftmay be indicative of the movement of red blood vessels in blood throughan artery or vein relative to the device 102 over time. The reflectedsignals may, when measured, produce values distinct from all othervasculature, which may facilitate isolation of reflected signals from avessel of interest. The measured Doppler shift over a span of time maybe measured to calculate a velocity time integral that is indicative ofthe amount of blood passing through a cross section over the span oftime.

The device 102 may be configured to perform automated functionalhemodynamic assessments in a vessel (e.g., a carotid artery, brachialartery, femoral artery, etc.). For example, in some embodiments, thedevice 102 may be perform auto-focusing of an ultrasonic source (e.g.,an ultrasound probe) at a number of different depths and angles, andthen collect data that best fits the structure of a targeted bloodvessel. In some embodiments, the device 102 may include a chain oftransducer pairs oriented in a saw tooth pattern such that, in concert,the transducer pairs produce overlapping ultrasonic waves at an angle ofincidence between about 25 degrees to about 60 degrees in respect of aplane of fluid flow (e.g., the direction of blood flow through a bloodvessel) through the at least one targeted blood vessel.

According to some embodiments, the saw tooth arrangement of transducersmay function to aim the ultrasonic beam so as to reliably generate anangle of incidence of about 25-60 degrees (or thereabout) with a generalanatomical angle (for normal body types of 45 degrees). Use of thisangle may enable reliable detection of reflected ultrasonic signals fromthe body part of the individual containing the vessel of interest towardwhich the ultrasonic beam (e.g., a continuous beam or pulsed beam) isdirected without the intervention of a specifically trained technicianor other individual. Acceptable angles, in accordance with someembodiments, include 45+/−1 degrees, +/−2 degrees, +/−3 degrees, +/−4 .. . +/−20 degrees, among others.

Current methods require careful placement of ultrasonic monitors, oftenrequiring the skill of an expert or trained individual in order toensure effective readings. According to some embodiments, the saw tootharrangement of transducers functions to make available a plurality ofredundant, but effective, placement options on the body part of theindividual, thus making it less difficult to obtain an effective readingfrom the vessel of interest. The saw tooth pattern of the array may beoriented such that co-planar elements all have the same or about thesame angle (e.g., relative to the skin) such that an unfocused curtainof ultrasound is emitted, the unfocused nature of the ultrasoundallowing for a series of redundant positioning points for positioningthe device 102.

The redundant positioning may allow for the device 102 to be used by aless skilled or, in some embodiments, even an unskilled user. Further,redundant positioning is helpful in emergency situations where non-idealconditions in conjunction with a need for speed (e.g., individual isotherwise in great pain or dying), even for the skilled practitioner.

According to some embodiments, multiple transducer element pair designs,such as the saw tooth pattern, may also enable multi- or single elementactivation depending, for example, on the quality of the reflectedsignal received from the vessel of interest. For example, where a multitransducer element array containing eight elements receives a reflectedsignal from a vessel of interest that is sufficient to allow effectivefunctional hemodynamic monitoring with just two of the transducerelements, the remaining six elements may be de-activated or may enter alow power mode. This may provide benefits to power consumption andefficiency of operation (e.g., computational efficiency) and vesselidentification.

The device 102 may be functional to perform automated functionalhemodynamic assessments of a number of types of blood vessels. Dependingon a particular vessel operable with the device 102 at a certain time,different depths and angles may be selected. The selection, for example,may be automated, based on the application of various pre-programmedinstruction sets. The selection of such parameters is a non-trivialtechnical problem in view of variations of human physiology, bloodvessel types, and practitioner skill levels. Further, the device 102 mayoperate, in some embodiments, such that it may be operable by unskilledpractitioners and/or practitioners having less training (who may need torely on the device 102 to select parameters based on sensed data and/orinput data). The data retrieved from the ultrasound unit may beutilized, for example, to calculate relative blood flow (e.g., amount ofblood/heart beat or unit time), and a potential advantage may enablevariance in how the probe is oriented to the particular vessel beingexamined.

The device 102 may be configured to detect relative blood flow (in oneor more directions, such as forward or backward flow) through aparticular vessel (e.g., the carotid artery, brachial artery, femoralartery, jugular, etc.). The device 102 may further be configured toindicate the level of cerebral perfusion that has occurred. The device102 may further be configured to indicate whether the return ofspontaneous circulation (“ROSC”) has occurred. Where functionalhemodynamics are measured during CPR, the device may be adapted tomeasure functional hemodynamic parameters (e.g., fluid dynamics) in a“binary” mode (i.e., fluid is either flowing through a vessel, or it isnot). In other embodiments, the device may be adapted to provide arelative measure of a hemodynamic parameter such as the amount of fluidflowing through a cross-section of the vessel over a particular periodof time (e.g., carotid, femoral, brachial, etc. blood flow rate).Measurement of relative carotid flow rate may be the most effective wayto automatically detect ROSC. In detecting and determining ROSC, someembodiments of the device are configured to apply signal processing toidentify indicative waveforms (e.g., “shark-fin shaped” pulses, or othertypes of pulsatile-type waveforms or cardiac waveforms) which may be outof synchronicity or occur out of phase in relation to chestcompressions.

In a specific example, the identification of one or more “shark-finshaped” waveforms may, for example, be indicative of a ROSC event. A“shark-fin” shape, for example, may include pulses having one or morerounded curved sections, for example, on a leading and on a trailed edgeof a pulse. In Applicant's experiments, the “shark-fin” shape was foundto be particularly representative of ROSC events.

Other shapes are also possible (e.g., pulsatile-type waveforms orcardiac waveforms), and they are indicative of ROSC events whendetermined to be out of synchronicity or occur out of phase in relationto chest compressions. When these out of sync/out of phase shapes areidentified and determined to be more prevalent than potential noiseartifacts, the device 102 can be configured to alert the rescuer toimmediately stop compressions (potentially limiting damage in emergencysituations).

As described in further embodiments, there may be various methods and/ortechniques to aid in affixing and immobilizing the ultrasound unit(e.g., an ultrasound probe) to the local site on the patient in order toimprove accuracy/fidelity of repeat measurements and, in someembodiments, provide real-time monitoring. For example, adhesives,tensioning bands, collars, pillows, etc. may be utilized. In someembodiments, housing is provided to which vascular probes could beattached and fixed to the neck at varying angles.

In some embodiments, the device 102 may be configured to communicatethrough one or more communication links (e.g., wired, wireless,cellular, local area networks, wide area networks, infrared, Bluetooth™)with one or more receiver computing devices (e.g., for further analysis)and/or downstream computing devices (e.g., a data centre associated witha healthcare facility). Accordingly, the device 102 may or may not havea display 110.

For example, the device 102 may be configured to provide outputs thatmay inform the function of other devices. The output of the measure caninform various individuals and/or machines of various hemodynamicparameters (e.g., features of the flow of blood through a vessel). Forexample, machines delivering cardio pulmonary respiration (CPR) canprovide feedback on the efficacy and timing of chest compressions. Thereader will understand that many other applications may be contemplated.For example, the device 102 may be configured to benchmark the velocityof early chest compressions (when the rescuer is fresh) based on first3-10 chest compressions, then interpret the velocity of the blood oneach compression with and providing an output (e.g., an alert, a signal,a visual indication) that informs the rescuer on how close to achievingthe same efficacy in each subsequent chest compression. The feedback tothe rescuer is particularly useful where the rescuer is not particularlyexperienced or skilled, and the feedback may be modified to indicate,for example, relative instruction sounds (e.g., a voice indicating “lastcompression was less effective than prior compressions), or other typesof visual indications.

The device 102 may have various components to detect (e.g., monitor,track, probe, sense, determine, identify, investigate) various physicalcharacteristics of the patient.

The device 102 of FIG. 1 may be used in conjunction with specificworkflows that may be adapted such that the device 102 and the workflowsinteroperate to provide accurate and repeatable localization (e.g.,using the ultrasound readings).

The portable ultrasound unit may, for example, be a continuous waveDoppler ultrasound module that is capable of emitting ultrasonic wavesin a continuous beam, and that is accurate and fast enough to provide areal or near-real-time analysis of parameters of the fluid flow in theblood vessel, and in some embodiments, is free of a bulky cart or cord.The device 102 may, for example, be portable enough to be carried aroundby a physician (e.g., for extended periods of time) or stored forsharing by multiple practitioners (e.g., in a ‘grab-and-go’ chargingstation for physicians).

In other embodiments, a pulsed wave Doppler ultrasound may be providedinstead.

Continuous wave Doppler ultrasound modules may function to measure fluidvelocities along the entirety of a scanned channel. For example, wherethe scanned area is a blood vessel, a continuous wave Doppler method maymeasure the velocities of fluids traveling through the entire scannedportion of the blood vessel over a period of time. In contrast, pulsedwave Doppler ultrasound modules may only allow measurement of fluidvelocities at a single point, or a very finite sequence of points, alonga scanned channel.

Pulsed wave Doppler ultrasound modules may function by emitting a pulsedsignal toward an area of focus for a finite period of time, then ceasingthe emission of said signal and monitoring received signals in order torecord a reflected frequency shift related to the original emittedsignal for a finite period of time. This process is then repeated. Oncethe reflected signal is received, a processor calculates the velocityand flow of liquid through a channel at the area of focus (e.g., a bloodvessel). Since pulsed wave Doppler ultrasound techniques require afinite signal emission period and a second finite signal monitoringperiod, there is a limit to how fast said techniques can accuratelymeasure the flow of liquid through a channel—where the velocity of thefluid surpasses a certain point, temporal aliasing (a phenomenon wherebya recorded signal appears distorted due to a recording system with aninsufficient sampling rate). This mode of operation can be described as“half-duplex”.

Continuous wave Doppler ultrasound modules function by emittingultrasound signals in a continuous beam along a channel and continuouslymonitoring the multitude of reflected frequency shifts via a detector.This mode of operation can be described as “full-duplex” as thecontinuous wave Doppler ultrasound is continuously emitting andreceiving signals. A potential advantage realized by this mode is thatit enables the measurement of high-velocity flows of liquids throughchannels (e.g., blood through blood vessels) that could not beaccurately measured using pulse wave Doppler ultrasound techniques dueto the above-described temporal aliasing problem.

The device 102 may further include and/or be associated with a locatingdisposable that may be affixed once to the patient for variousmeasurements, the measurements of which can be compared with oneanother. The device 102 and/or the locating disposable may require alevel of ease of use and sufficient accuracy such that practitioners andcare centres may readily adopt its usage.

The device 102 may be battery powered and may use a transducer arraywhich may function to measure the Doppler shift produced by fluidpassing through a vessel (e.g., a Doppler shift produced by red bloodcells in blood travelling through an artery relative to the position ofthe device 102. A technical challenge arises in relation to ensuringthat the device 102 is configurable to identify (e.g., delineate,distinguish) flow through particular vessels (e.g., distinguish carotidflow from the jugular vein or other confounding objects).

In operation, a patch-like (or collar-style) probe may be adhered tolocal area of skin on a patient under which the patient's carotid artery(or other vasculature) passes. The probe may utilize ultrasound signalprocessing methods (e.g. Doppler signal processing functions) toidentify pulsatile flow. When the ultrasound (e.g., continuous waveDoppler) function of the ultrasound signal is directed at an opposingangle to the blood flow, a velocity-time trace may be obtained. Bydefining one cardiac cycle (pulse/heart beat), a unit time may bedefined.

Calculating the area under the velocity-time curve (i.e., the calculusintegral), the device 102 and/or a downstream device may utilize thedata to determine the velocity-time integral (“VTI”), and the VTI may bemultiplied by the cross-sectional surface area of the vessel over thetime of one cardiac cycle (heart beat). The velocity time integral isproportional to the volume of blood that flows through a vessel per unittime. Therefore, it is a surrogate for cardiac output, which is animportant hemodynamic parameter (e.g., a proxy that can be obtainedbased on measured physiological indicators).

The VTI can be used, for example, to track an average of VTI over aperiod of time prior to performing an intervention (30 s window),perform an intervention (30 s window), and to calculate average VTI overa period of time after performing an intervention (30 s window). In thisexample scenario, the VTI is used as a proxy to determine the efficacyof the intervention, which is useful feedback in emergency situations.For example, a portable blood flow monitoring device 102, on detectingeffective treatment, may indicate via tactile (e.g., vibration motor),auditory (e.g., speaker) or visual (e.g., GUI) mechanisms that CPRshould stop, potentially preventing additional trauma to the patientthat otherwise would have occurred if CPR continued (e.g., broken ribs,sternum fractures, internal organ damage).

Accordingly, an automated physical measurement of a blood flow throughthe vessel per heartbeat may be obtained using an ultrasonic approach.

In some embodiments, an auto focusing mechanism is provided, where thedevice 102 may conduct a validation protocol to identify which settingsare optimal (e.g., frequency, angle) for the patient's body, patchplacement, and/or other parameters. A challenge with conventionaltechnologies is that the selection of these signals is non-trivial andmay often lead to a high level of training required. For example, insome embodiments, this aspect of the technology aids in allowingun-trained or less trained personnel to use the device 102 reliably.

A computing device may apply an algorithm in conjunction with detectedreadings to determine the patient's velocity time integral (VTI,pre-challenge); prompt the physician for a fluid challenge (e.g.,passive leg raise); detect and/or calculate a post-challenge VTI; anddeliver an assessment of the patient's fluid responsiveness (increaseof >10% VTI or output following fluid challenge). A ratio may be foundbetween pre and post-challenge VTIs, and other thresholds may be usedfor assessments (e.g., 10%, 5%, 3%, etc. and may be indicative of anincrease or decrease). Where a condition is broken (e.g., as providedthrough a predetermined rule), or a trigger value, a notification may begenerated and/or provided (e.g., an alert, a sound, a display, apop-up).

A display may, for example, aid the physician by providing various typesof views, some views having various transformations (e.g., a simplifiedview), annotations (e.g., display markers, dynamic markers), analytics(e.g., determined aspects, averages, means, medians, identifiedaberrations), and/or a raw data view. For example, a post-/pre-VTI ratiomay be determined, and a 10% or greater ratio may be indicative of afluid responsiveness condition. Accordingly, some embodiments may beutilized to detect and/or determine various characteristics in relationto a carotid anomaly, or detect a carotid anomaly or an anomalyregarding another vessel of interest (e.g., brachial artery, femoralartery, etc.).

There may be other types of ultrasound devices that can perform flowmonitoring, however, drawbacks with conventional devices may be thosetypical of a multipurpose device: they are large, difficult to use, andmay often require lengthy training or experience.

The device 102 of some embodiments may be configured such that there mayonly be a minimum level of required hardware to effectively monitorblood flow, and may reflect a trade of multi-functionality for size,providing additional benefits as in relation to operation for use withcarotid flow procedures. At FIG. 2, a conventional ultrasound unit, theGE VScan™ 202 is pictured, having a display 204, and a probe 206.

Other catheter-based technologies may also be used for hemodynamicmonitoring, but the conventional products may be cumbersome and add riskin the context of various procedures. Pulmonary artery catheterizationis another technique that may be available for hemodynamic monitoring,wherein a catheter is inserted into the pulmonary artery via the venacava to directly measure cardiac output. Pulmonary arterycatheterization can measure right atrium, right ventricle, and pulmonaryartery pressure, as well as left atrium input pressure, but a majordrawback is that the catheterization is invasive and limited to surgicaluse. Pulse Pressure Waveform Analysis (PPWA) is another technique thatutilizes the arterial waveform, obtained either from an arterialcatheter or a finger probe, in order to calculate the stroke volume (SV)and the systemic vascular resistance (SVR), but complications may arisein view of non-linear and varying arterial wall compliance.

Phase shift technology/bio reactance approaches may be considered foruse, wherein when an AC current is applied to the thorax, the pulsatileblood flow taking place in the large thoracic arteries causes theamplitude of the applied thoracic voltage to change. Research, however,has indicated poor performance in relation tocritically-ill/post-operative patients; further, this approach may behindered by environmental factors, such as overweight or patients whichperspire heavily. Gas rebreathing techniques may also be used inrelation to estimating cardiac output (CO) non-invasively, but whileeasy to use, they have been shown to be adverse affected byspontaneously breathing patients. Septic Shock Algorithms may useaggregated historical data to predict the onset of septic shock, whichcan be diagnosed through blood pressure readings.

In some embodiments, the device may produce outputs functioning to allowdetection of various types of compensated shock. Compensated shock maybe defined, in an adult example, as systolic blood pressure above 90 mmHg while exhibiting signs of inadequate perfusion (e.g., tachycardia).In such situations, the device may transmit an alert signal via asensory output device.

In an example method, compensated shock can be determined as a ratiobetween HR/systolic blood pressure. However, this is not a verysensitive method as blood pressure takes a long time to change duringshock.

An improved method of some embodiments determines/generates a predictionof compensated shock by generating a comparison between heart rate andthe measured velocity time integral (e.g., a HR/VTI ratio). The improvedmethod generates a more sensitive marker as VTI corresponds moredirectly to the state of the heart. Accordingly, the improved approachenables earlier detection of patients in compensated shock. For example,in some embodiments, the device is configured to determine/flag changesin in the HRNTI ratio, and as the ratio becomes larger, the patient isflagged as potentially entering into shock (and corresponding workflowsmay be invoked, for example, to generate one or more alarmnotifications).

FIG. 3 is an illustration of an example neck profile, according to someembodiments.

Patients may have differing anthropometric parameters, including, forexample, carotid anthropometries, neck anthropometries, etc. Theseparameters may be taken into consideration, for example, as the devicemay need to be fitted on to and/or used in close proximity to bodilyfeatures of the patients, and thus may need to be calibrated and/oraccurately positioned.

For example, the minimum size (i.e. length) of the neck may determinethe maximum size of a body mounted device. The neck length for thesmallest 5% of the population is roughly 8 cm, and accordingly, themaximum comfortable height of the device may approximately be 8 cm.

Neck circumference also varies from person to person. The smallest neckcircumferences may be about 312 mm, and the largest about 463 mm. For around or square device (e.g. 8 cm in diameter or 8×8 cm square), thepatient's neck would have to conform roughly 14 mm at the edges, toomuch for patient comfort. If the device were curved, the neck would haveto only conform roughly 5 mm, but a curved feature may add complexity(and likely size) to the device and/or components thereof.

As indicated in FIG. 3, the neck anatomy may be fairly consistent frompatient to patient. For example, the internal diameter of the CommonCarotid Artery (CCA) may be approximately 6.2 mm for women and 6.5 mmfor men, ranging between 4.3 and 7.7 mm in maximum and minimum sizes (asnoted in a study having a study size of 123). The standard depth for apatient's CCA may be 20-40 mm below the skin. The wall thickness may beroughly 0.75 mm. Additionally, the diameter of the CCA may expandroughly 0.5 mm with every heartbeat.

Another study suggests that the ratio of the internal carotid andexternal carotid artery diameters can be predicted as approximately 0.65and 0.58 respectively (e.g., each is roughly ½ to ⅔ of the diameter ofthe CCA). The vertebral artery may be hidden in bone, very far away andvery small. The jugular vein has blood flowing in the opposite direction(therefore “up” may have to be established).

Directional information can aid in the assessment of position.Dimensional measurements can also be used to aid in position by assumingany measurement of a vessel that is 5 mm in diameter and is less than4.3 mm deep is likely not the CCA.

Furthermore, a relationship can be established between distance anddiameter of the CCA. A CCA further from the skin implies a larger bodiedpatient, who would be expected to have a larger CCA.

One study placed the ideal measurement location at 15-20 cm below thebifurcation. The subclavian artery sits very close to the clavicle, andthe CCA bifurcation is near the larynx (Adam's apple) meaning areasonable measurement location is anywhere from 5-20 cm above theclavicle, or midway between the larynx and the clavicle.

Patients with larger neck diameters are likely to have a thicker layerof cutaneous tissue between the probe and the CCA. No papers studieddescribed a correlation between bariatric patients and difficulty inreading CCA flow, meaning this may not be an issue. It may also meanthat the full sized ultrasound machines currently in use are variableenough to account for these differences. This patient profile may not besuitable for the AFRU. In some embodiments, multiple transducer pairsmay be arranged end to end to form the transducer array. This may enablethe device to contour to different patient morphologies on the neck,arm, torso and/or thigh, etc.

FIG. 4 is a depiction of a CCA flow measurement angle, according to someembodiments. A probe 402 is shown for measuring flow in relation tovessels 404, being incident flow at plane 406. Accordingly, sampleimages 408 (greyscale) and 410 (color) are shown.

Applicants considered various approaches to the ultrasound unit and madevarious decisions related to the design. In some embodiments, theultrasound unit may include a transverse and oblique array.

Other possible approaches included a single transducer ormultidimensional transducers (i.e., a 2D array or a scanning 1D array).Though these other approaches still have a possibility of success, thetransverse oblique array may be preferable in some embodiments. Thearray may be oriented obliquely (as shown by the line indicative ofplane 406) to pass through the CCA such that the array can readanatomical information in the transverse plane, and Doppler signalprocessing information in the longitudinal plane.

In this architecture, there is a risk that suitably effective Dopplersignal processing measurements may be difficult to obtain with atransversely oriented array. There is also risk that many elements willbe required, resulting in a higher cost and size of the device.

FIG. 5 is an illustration of an example tensioning mechanism formaintaining acoustic coupling between a device 504 and a body part 502according to some embodiments. The device 504 housed in a housing 512which may adhere to the surface of a body part 502 containing a vesselof interest. The housing may further contain a tensioning cover 510which may be coupled on one side to the device 504. The housing mayfurther contain two or more latching mechanisms 506 which may besituated perpendicularly to the body part 502 of the individual andwithin the housing 512. The latching mechanisms may each contain aplurality of latching channels 506 a-f which may function to receive theedges of the tensioning cover 510 when downward force is applied theretoand hold the tensioning cover 510 in place, thereby causing thetensioning cover 510 to maintain position and, by extension, applydownward force to the device 504 such that it remains secure against thebody part of the individual 502. This may cause the device 504 to besituated such that it maintains a position functional to produce acorrect signal and read a correct reflected signal to and from thevessel of interest (e.g., within a correct range of distances from thevessel of interest).

FIG. 6 is an example block schematic diagram of a device, according tosome embodiments. FIG. 6 illustrates an electrical architecture and mayinclude various elements of electronic circuitry, etc. The device may beimplemented in various forms, including, for example, by software,hardware, embedded firmware, and/or a combination thereof.

A user interface 602 may be provided for various input I sensory-outputfunctionality, including the ability to receive parameters, etc. fromusers (e.g., patients, clinicians). Output functionality may be used to,for example, provide a graphical interface for clinicians and/or tocommunicate information to downstream computing systems (e.g., aclinical data center).

There may be various data storage units included for storing data (e.g.,raw data, pre-processed data, processed data, post-processed data), andthere may be one or more processors 604 utilized for conducting variousdeterminations and/or calculations. The device may also, in someembodiments, have on-board memory that may be used to support variousfunctionality, such as processing data for display to a clinician, etc.Various peripherals 606 may be utilized to provide various input signalsand/or to receive various outputs (e.g., through USB, Bluetooth, etc.).The processor 604, for example, may be configured to control theperipherals 606, and the user interface 602. Ultrasound components maybe provided, for example, through an ultrasound front end 612, a probe,transducers 616 a . . . 616 n, which may be placed on and/or inproximity to a patient 618. A power supply 610, (e.g., a battery), maybe utilized to supply power to the ultrasound components.

In some embodiments, the user interface 602 may be provided on aseparate computing device, communicating with the Central ProcessingUnit (“CPU”) 604 via one or more Peripherals 606, hence the userinterface 602 is depicted as connecting to the CPU 604 via a dashedline.

In operation, the front end may be provided and, in some embodiments,may include an eight-channel integrated circuit that may include theultrasound front-end 612, the probe 614, and the transducers 616 a . . .616 n. Signals passing through the front-end first may be amplifiedand/or filtered, and then passed through an anti-aliasing filter whichmay remove frequencies that may be too high to be sampled. These signalsmay then pass through an analog-to-digital converter and may be providedto a configurable integrated circuit (e.g., a field programmable gatearray (FPGA), or a custom integrated circuit) 608 as, in someembodiments, by low-voltage differential signals (LVDS).

An ultrasound emitter (not shown) may be utilized to produce thehigh-voltage signal needed to drive the ultrasound transducers. Theemitter may be provided a positive voltage supply +610 and a − negativevoltage supply 610 that is controlled by low-voltage logic signals fromthe configurable integrated circuit. Other voltages and/or powersupplies may be utilized and the above is provided as an example.

The configurable integrated circuit 608 may be configured to control theemitter and receive logic signals from the front-end. The configurableintegrated circuit 608 may be configured to perform digital signalprocessing that may be utilized to both send and receive signals,including beam-forming and Doppler shift computations.

The CPU 604 may host the operating system of the device, and may liaisebetween the configurable integrated circuit 608, user interface (UI) 602and any peripherals 606 that may be added to the system and/or performpost-processing on signals received from the configurable integratedcircuit 608.

The UI 602 may include an LCD touchscreen and/or an LCD screen withbuttons. Other types of displays may be contemplated. Indicator lights,comprising for example LEDs, and indicators sounds generated from aspeaker may also be part of the user interface 602 to provide feedbackto the operator. In some embodiments, feedback corresponds to operatingconditions of device 102 in order to direct the operator to orientdevice 102 to a desirable and/or acceptable local site on the patient.The purpose of this direction may be to permit full operability of thedevice with a minimum of training or experience. If the device isrequired to be connected to the cloud, an onboard W-Fi module can beincluded along with additional peripherals 606 such as Bluetooth or USB.

A printed circuit board (PCB) may be provided to host some or all of theelectronic components within a structure (e.g.; a housing, a base). Insome embodiments, the device may be powered by a rechargeable orreplaceable battery, which may be used to drive both the ultrasoundand/or the other electronics (e.g., LCD screens, etc.).

As size is a consideration, lithium-ion technology may, in someembodiments, be selected as an option for compact power density.Operating under the assumption that these batteries typically can store77,000 Ah/cm3 (amp-hours per cubic centimetre), the battery in thedevice may have to be, for example, 125 cm3 for 1 hour of continuousactive use. A Li-ion battery of this size typically weighs about 250 g.Additional lifetime can be achieved by adding a larger (and heavier)battery, which may be suitable for a larger embodiment.

FIG. 7 is illustrative of some example components that may be utilizedfor interfacing with a patient's body, according to some embodiments.The method with which the device interfaces with the body may be animportant factor for consideration. Such a component, for example, maybe a “disposable” to connect (acoustically) the probe to the skin, andconnect (mechanically) the device to the patient. Sample disposables areindicated at 702 and 704.

In some embodiments, the disposable may integrate these aspects forquick application and disposition. This may avoid the disadvantage ofapplying ultrasound gel separately, which creates variability and mess.

In some embodiments, an approach includes combining the requirementsinto one solution: applying an acoustically transmissive adhesive (i.e.,the adhesive also serves as the gel).

In some embodiments, the requirements may be separated: a material isprovided for acoustic coupling and a material is provided for physicalconnection.

An example design may include utilizing an adhesive ring with a gel padcenter. The adhesive connects the device and the gel (solid or liquid)provides an acoustic connection. The user would simply peel back theinside of the disposable, stick it to the device, and then remove thecover of the patient side immediately before application.

The disposables may not need to be sterile (unless applications to openwounds are included in the indications), but should be held to a levelof cleanliness typical of the industry.

Disposable ultrasound pads such as Rich-Mar AutoGel™, BlueMTech™ andAquaflex™ ultrasound gel pads, may be provided to replace ultrasound gel(for the purposes of limiting cleanup) and may be utilized with thedevice. These pads may need to be wetted with water, and a standoff padmay be used to position the probe away to get a clearer picture ofsuperficial areas of the skin (for example, ATS™ phantoms).

In some embodiments, a custom sized block can be centered under theprobe head, adhered on one side to the device and covered on the otherside by a dust cover that also keeps the disposable wetted.

As an alternative, ultrasound gel may be utilized. Gel could bepre-applied in a cavity in the disposable. A similar peel-back covercould expose the gel and make it ready for application. After use, thegel may have to be wiped off the patient.

An alternative method of acoustic coupling is a liquid filled pad.Similar to an ultrasound pad in its function and composition, these bagsare filled entirely with liquid. A thinner liquid eliminates thelikelihood of bubbles in the medium, but adds issues at the wallinterface and with filling. For these reasons, liquid pads may be a lessdesirable alternative to those listed above.

In some embodiments, a tensioning material (e.g., a tension bandage) maybe positioned around the body in order to provide a force normal todevice 102 and ensure sufficient acoustic coupling.

In some embodiments, adhesives may also be utilized. FIG. 8 depicts anexample adhesive by 3M™. Adhesives may by hypo-allergenic and may stayin place for a number of days. The adhesive 802 may help keep a deviceand/or a portion thereof positioned in the target local site on thepatient.

Silicone may be used as a protector and an acoustic coupling materialfor the probe/human interface, often used in conjunction with gel. Forlimited movement across the patient's skin, (e.g., with some embodimentsof the device), the need for gel may be reduced and silicone alone mightbe effective. A drawback to silicone is a reduced speed of sound, whichmay require an algorithm to correct. Calculations performed by the CPU604 may be affected based on a pre-programmed speed of sound throughlayers used to connect to the patient. In some embodiments, the user isprompted to provide data to the device either through the UI 602 orthrough a device that is coupled via the communication peripherals 606so the CPU 604 can adjust the calculations performed based on thecomposition of the layers between the transducers and the patient'sskin.

The device may require a mechanical housing that may vary in detailbetween embodiments. A rigid two part housing, for example, may besufficient to provide a structure, with standoff points to hold theelectronics. The housing may include spacers between components to avoidrattle or internal movement. The housing may need to be cleanable, andso may include gaskets to prevent water ingress at the seam, display,and buttons (keypad membrane).

Heat management may be an important consideration. The device mayconsume significant amounts of energy during use, and accordingly, thehot features of the device may need to be kept away from the patient toreduce the risk of burning (e.g., must be less than 43° C. per ISO60601).

If the heat generation is excessive, numerous strategies can beutilized, such as insulation or heat fins, designed inconspicuously intothe exterior of the housing. A plastic housing may be a naturalinsulator but may cause the electronics to overheat. Active cooling witha fan is also possible.

A metal housing may have advantageous attributes: protecting theelectronics at the expense of patient safety. If an embodiment isapplied that does not connect to the patient directly then heatprotection may not be a requirement.

If the housing is plastic, injection moulding can be used formanufacturing. If a metal housing is used, numerous options areavailable, though some may be more costly than injection moulding

In some embodiments, the device may be provided as a single part. Insome embodiments, the device is provided in having two or more parts;these parts may comprise a body, a probe, a separate computing device, astand-alone cart, among others. For these embodiments, a probe wire maybe provided to connect the body of the device to the probe.

Wires for this should be strong enough to avoid pullout if the patientmoves or the device falls. The probe itself (or the connecting surfaceon a one-part device) may benefit from a silicone interface piece, toprotect the device and allow some conformity.

FIGS. 9A-9C, 10, 11A-11C, 12A, 12B, 13A-13C, 14A-14B, 16, 17 may beillustrative of some sample embodiments of the device.

FIGS. 9A-9C illustrate a pocket-sized embodiment; FIG. 9A provides a topelevation view, FIG. 9B provides a perspective view, and FIG. 9Cprovides a side cross-sectional view, according to some embodiments.

As depicted in FIGS. 9A-9C, an embodiment may include a pocket sized,body mounted ultrasound device that can be carried around by a clinician(e.g., the attending physician). The device may have an adhesive ring902, a body section 904, and/or a display 906. The adhesive ring 902 mayprovide an adhesive force between the periphery of the body section 904and the local site on the patient's skin. A concave space 908 may beprovided for a gel pad or liquid gel.

The size of this embodiment may be reduced by using a number ofstrategies, including, for example: offloading processing and display toanother device such as a tablet (or smartphone), changing its geometryto rest partially elsewhere, measuring flow in a different artery (toreduce comparative size), or reducing the battery life or removing itentirely (plug-in power only).

FIG. 10 is an illustration of a pocket-sized embodiment. The embodimentmay have display 1004, a power button 1002, and other buttons 1006 and1008 that may be used, for example, to perform various input and outputfunctions.

FIGS. 11A-11C may be illustrative of a small embodiment with a coupledprobe, according to some embodiments.

FIG. 11A is a front perspective view of the embodiment; FIG. 11B is arear perspective view of the embodiment; and FIG. 11C is a partial viewof the embodiment. The device, may, for example, have a display 1102,control button 1104, power button 1106, an integrated handle 1108, acable management apparatus 1110, a probe 1112, a charging port interface1114, a printed circuit board stack 1116, and a battery 1118.

The footprint and height of the device illustrated in FIG. 11A-11C insome embodiments may be approximately 6×6 inches and 4 inchesrespectively.

A coupled probe may provide a lower risk alternative to the pocket sizedunit, while still being small and portable. The adhesive probe-patch maybe coupled to the base unit via a cable.

The clinician (e.g., a physician) may place the unit on the examinationtable anywhere within range of the patient's neck, and extend andconnect the probe. The probe may stay in place during the examinationand possibly longer (for repeated exams). The device may be powered by alarger, more powerful battery than possible in a pocket-sized unit, butis also can support a wall plug for heavy use.

As the device may (in some embodiments) be too large to be carriedaround constantly, the device may be left at the charging stationbetween patients, further extending battery life. The device may also belarge enough to carry a gel holder, or an area to keep extradisposables. The device may include W-Fi and/or Bluetooth connectivity,or can transfer data via a base station. In other embodiments, thedevice may be miniaturized for portable use.

FIGS. 12A-12B and FIGS. 13A-13C may be illustrative of a smallembodiment with integrated probe, according to some embodiments. FIG.12A is a side view of this embodiment, and FIG. 12B is a perspectiveview of this embodiment. FIG. 13A is a perspective view of a secondversion of the embodiment with integrated probe being held at a handle,FIG. 13B is a perspective view of the second version; and FIG. 13C is aside view.

For example, the embodiment may include a probe 1204 for use with apatient 1202/1310, a base 1206, a display 1208/1306, and an adjustableneck 1210/1305. In some embodiments, a handle 1312 is provided. In theseexample embodiments, the device does not have a separated probe.Instead, and area of the main chassis contains the ultrasound head whichmay be placed against the patient.

Similar to the coupled probe model described above, these embodimentsmay contain a larger battery, a plug, wireless connectivity, and maycontain storage for disposables. The embodiments may be simpler indesign and use than the coupled probe, and more durable. A disposablemay not be necessary, or if necessary may be a simpler disposable.

A cart embodiment is shown in FIGS. 14A and 14B; FIG. 14A is a frontperspective view of a cart embodiment, and FIG. 14B is a side elevationview of the cart embodiment. The application on a medical cart mayprovide some advantages. For example, the central architecture does notdiffer significantly from other carts: the device 1402 may be providedon a cart apparatus 1406, having a handle 1404, and a base 1408. Theembodiment may include a computer, monitor and screen 1410, with anultrasound probe 1412

The cart embodiment may also avoid logistical issues that may be presentwith portable units: for example, the embodiment may be unlikely to belost or dropped, it may not require an area on the patient's bed to bepositioned upon, and can be easily plugged in (or battery powered) withroom for a long cord. The device may also not require an includedcharging station, and may thus be marketed as an individual unit.

The device may include a chassis 1206 and a user interface 1208 (i.e., alarge touchscreen), and a probe 1204 that may differ significantly fromother ultrasound units.

The probe 1204 may include a small adhesive patch at the end of aconnection cable 1210 which can be installed on the patient and remainsstuck during the procedure (or longer). The software may be configuredto automatically find the CCA and to obtain readings, displaying onlythe results to the clinician (e.g., a physician) and eliminating theneed for ultrasound expertise.

Some embodiments are adapted to respond to a protracted period ofpatient care. An example patient-care profile 1500 is provided in FIG.15. Assessment of functional hemodynamic parameters (e.g., fluiddynamics) may be desirable at each phase of the patient-care profile1500. Different care-providers may be responsible at designated phases.A functional hemodynamics measurement device that is unique to a patientmay be desirable in order to provide continuous monitoring betweenphases and care-providers. Similarly, a functional hemodynamicsmeasurement device that is unique to a care-provider may be desirable toprovide monitoring of functional hemodynamics measurement to a pluralityof patients.

A cross-sectional view and overhead view of some embodiments of thedevice are provided in FIG. 16 and FIG. 17 respectively. In someembodiments, an adhesive 1606/1704 may be employed to fix the device tothe local site on the patient's skin; a tensioning material 1608/1708may further be employed to apply a force normal to sensor housing1612/1712, and towards the local site in order to fix the devicerelative to the local site. The tensioning material 1608/1708 maycomprise a band, to be slug around the patient in order that tension maybe adjusted by altering the length of upstretched band. The tensioningmaterial may further be elastic, in order to eliminate discomfort to thepatient, and also continue providing sufficient normal force while thepatient moves and the body change shape.

In some embodiments, sensor housing 1602 may contain a transducer array1602, electronics, including but not limited to a visual display,speakers, and/or battery 1610, and other electronics. In someembodiments, sensor housing 1612 is shaped like a half of an ellipsoidor American football.

In some embodiments, the sensor housing 1612 may contain a userinterface unit 1620, which may be a sensory output device operable withthe visual display, speakers, and/or battery 1610. The user interfaceunit 1620 may function to communicate inputs generated by a userinteraction to the device. For example, the user interface unit 1620 maycomprise a sensory output device such as a capacitive touch input devicecoupled with a visual display 1610. The user interface unit 1620 mayfunction to allow the user to input selections that, when received bythe device, cause the device to modify its operation mode (e.g., userinput may cause the device to being a process operable to determine apre-intervention/post-intervention VTI ratio as described below).

In some embodiments, the transducer array 1602 comprisestransducer-receiver pairs, where the transducer component generatesacoustic waves, transferred into the patient acoustically through ahydrogel or acoustic coupler 1604. The acoustic waves travel through thepatient, and are modulated and reflected by media interfaces, forexample fluid within a blood vessel. Reflected and modulated waves aresensed by a receiver component in the transducer-receiver pair andwithin the larger transducer array 1602. In some embodiments, theDoppler shift in a frequency modulated signal generated by thetransducer 1602 may provide an accurate representation of the velocityof an element. In some embodiments, the element to be measured is thefluid flow within a blood vessel; non-limiting examples including thecarotid artery, the brachial artery, or the femoral artery.

According to some embodiments, a sensor consisting of a ultrasoundtransmitting transducer element 1804 and receiving transducer element1806 may be configured as depicted in FIG. 18 and FIG. 19, representinga cross-sectional view and an overhead view respectively. Transducerelement 1804 and receiving element 1806 may be configured such that theyparallel to each other, and each directed at a 45 degree angle to thetransverse plane (i.e., the plane defined by the surface of the skin1808 at the local site on the patient). The transmitting transducerelement 1804 and receiving transducer element 1806 may resemble twomatch-sticks, tangent along one edge, as depicted in FIG. 18. In otherembodiments, the transmitting element 1804 and the receiving element1806 are spaced apart laterally.

In some embodiments, the orientation of the transmitting transducerelement(s) 1804 and receiving transducer element(s) 1806 is configuredsuch that the angle between the vectors defined by the direction of theultrasound wave and the direction of blood flow is approximately 45degrees. The transducer element pairs 1804, 1806 can detect blood flowdirection by the sign (i.e., positive or negative) of the Doppler shift.The ability to track blood flow direction may aid significantly indiagnosing various ailments or determining whether one or morehealth-related events have taken place. For example, a change in bloodflow direction may indicate that the patient's wound has beensuccessfully sealed, that the patient's circulatory system is working(not working), CPR has been successful, the patient is bleeding out andrequires immediate attention, among others.

An increase in frequency (positive shift) indicates blood flowingtowards the ultrasound wave generated by the transducer element 1804.Similarly, a decrease in frequency is indicative of blood flowing awayfrom the transducer element 1804. In some embodiments, the acceptablefunctional range of transducer element orientations relative to theplane of the vessel being interrogated is about 45-degrees±15-degrees,with 45-degrees representing the preferred embodiment. If the vesselbeing investigated runs parallel to the skin line of the patient, theangle can be measured with respect to the skin line. The reader willunderstand that in some embodiments, the acceptable functional range maybe about 44-degrees±14-degrees, about 46-degrees±16-degrees, etc.

In some embodiments, the ultrasound wave (i.e., Doppler beam) is“unfocused”; that is, the beams sweep out an angle of approximately20-degrees, such that by directing the beam approximately 45-degreesfrom the transverse plane (as defined by the plane of the skin at thelocal site), the transmitting transducer element 1804 will generate awave that intersects with the blood vessel, and the angle of acceptanceof the receiving transducer element 1806 (also 20-degrees) is largeenough to receive the reflected and modulated signal generated by theblood flow. In this example, the width of the transmitting transducerelement face may be as small as 0.34 mm. This size is suitable forhigh-frequency (i.e., approximately 7 MHz) applications where high focalloss may be acceptable. Further, the width of the transmittingtransducer element may be as large as 2.15 mm. This size is suitable forlow-frequency (i.e., approximately 4 MHz) applications where only lowfocal loss is acceptable.

In another example, a beam that sweeps out approximately 60-degrees canbe constructed. The width of the transmitting transducer element facemay be as small as 0.924 mm. This size is suitable for low-frequency(i.e., approximately 4 MHz) applications where high focal loss may beacceptable. Further, the width of the transmitting transducer elementmay be as large as 1.52 mm. This size is suitable for high-frequency(i.e., approximately 7 MHz) applications where only low focal loss isacceptable.

In some embodiments, the functional frequencies of ultrasound wavesgenerated by the transmitting transducer element 1804 and detectable bythe receiving transducer element 1806 are approximately 2-8 MHz. In someembodiments, approximately 5 MHz may be the frequency generated by thetransmitting transducer element 1804. Typically, a lower frequency maydesirable for larger patients, as vessels such as the carotid artery,femoral artery, brachial artery, etc. are typically further below theskin surface 1808.

The orientation of the “match-stick” configured transducer element pair1812 may, in some embodiments, be fixed relative to the skin surface1808 by a tensioned bandage 1810, which provides a force normal to thetransducer element pair 1812 and directed towards the skin surface 1808.

In some embodiments, an audio or visual cue based on the Doppler shiftmeasured by the ultrasound transducer pair 1812 may guide the placementof the device relative to the local site on the patient. A strongersignal relative to the noise sensed by the transducer pair 1812 may beprocessed by the CPU 604 and outputted to a peripheral speaker ordisplay 606. The output may comprise, for example, a particular sound(e.g. “whoosh”), a change in volume, or frequency of beeps in the caseof an audio cue, or it may comprise, for example, brightness, number ofLEDs activated, the flashing of a pre-selected image, among others inthe case of a visual cue depending on the type of display provided.

In some embodiments, the sensor consists of a “chain” of transducerpairs 1812, as depicted in FIG. 19. Transducer pairs 1812 are mutuallyconnected (e.g. connected in parallel) via co-axial cable. The increasedlength to the overall sensor increases the acceptable area in which thedevice may be placed by increasing the likelihood that the target bloodvessel passes under at least one transducer element pair 1812.

In some embodiments, a “chain” may be preferable to a singular, butlonger transducer element pair 1812, because it may allow the housing tobe constructed out of a flexible material that in turn will betterconform to the various shapes and sizes of patients. Alternatively, insome embodiments, the transducer element may be made from a flexiblepolymer transducer material (e.g., a highly non-reactive thermoplasticfluoropolymer such as Polyvinylidene difluoride (PVDF)). This may alsoallow the housing to be constructed out of a flexible material andenable the housing to better conform to patients of various shapes andsizes. Producing the external housing in a flexible fashion mayfacilitate better acoustic coupling between the device 102 and the bodyand a higher signal to noise ratio.

In some embodiments, the transducer elements 1804, 1806 are made from apiezo-ceramic material. In some embodiments, each piezo ceramic element,representing an individual transmit transducer element 1804 or areceiving transducer element 1806 is 10×1×1 mm in shape. Thepiezo-ceramics in some embodiments may be a PZT-5A or PZT-5H or acombination thereof.

In some embodiments, the current draw is approximately 25 mAh. In someembodiments, the device may have a mode designed to conserve power andextend battery life. For example, the device may turn on only a pre-settimes or it may only turn on at the request of a user and automaticallyturn off (or “sleep”) after a defined period of time. FIG. 20illustrates an example surface profile of a matchstick element,according to some embodiments.

In some embodiments, the transducer element pairs 1804, 1806 may beadapted to generate and detect ultrasound signals from which a peakvelocity of the Doppler Shift, VTI, or thepre-intervention/post-intervention VTI ratio can be determined by aprocessor or other signal processing logic. The device 102 may,according to a pre-programmed instruction set, implement one or more“sampling windows” which may perform a calibration routine functional toeliminate the inherent variability of a detected Doppler signal. Thecalibration routine may: a) record signals detected by the transducerpair during a pre-defined span of time prior to the intervention (e.g.,10 seconds) as a “pre-intervention window”; b) cease recording signalsduring a corresponding pre-defined span of time during the interventionas an “intervention window”; and c) record signals during acorresponding pre-defined span of time subsequent to the intervention asa “post-intervention window”.

The VTI is determined, in accordance with a preferred embodiment, basedon a baseline sampling prior to intervention. During the time ofintervention, various measurements may be taken. Following intervention,a post-intervention sampling (on the same time period as baselinesample) is determined, and in the preferred embodiment, a VTI ratio isgenerated pre and post intervention. The post/pre VTI ratiodetermination is a useful, non-invasive technique that, providesclinical information relating to the patient fluid responsivenessstatus.

One advantage of the device is the ability to measure both heart rate(“HR”) and VTI. This permits the calculation of the HR/VTI ratio−anindex that (unlike the Shock Index) is not subject to vascularconstriction as a compensatory mechanism during the onset of shock.

In some embodiments, the design, orientation, and frequency of theultrasonic transducers are specifically designed to facilitate the rapidand repeatable measurement of the signal of interest (e.g., theultrasonic signal reflected from the vessel of interest). Subsequently,the measured signal of interest is automatically processed by the signalprocessing routine in order to generate an output.

Currently available point of care ultrasound machines require severalmanual steps to be completed in order to return a valid output. Further,successfully completing several of these steps requires users to havespecific training and skill. For example, currently available point ofcare ultrasound machines may require: manual identification of thevessel of interest using an ultrasound imaging screen; manualorientation of the angle of an ultrasound probe in relation to thevessel of interest to produce useful readings; manual identification ofthe vessel of interest to activate a Doppler function (e.g., a Dopplersignal processing function); maintaining a substantially motionlesspositioning of both the ultrasound probe and the body part containingthe vessel of interest; and manually executing a command in order tocause a reading to be taken. Further, often these steps must be executedrepeatedly in order to compare changes in outputs received pre and postintervention (e.g., pre and post introduction of a medicament).

In contrast, some embodiments described herein may: automate some or allof the previously described steps; remove or reduce the requirement formanual identification of a vessel of interest; remove or reduce therequirement to manually orientate the ultrasonic transducer(s) relativeto the body part of the person containing the vessel of interest; mayautomate the process of identifying a vessel of interest and activatinga Doppler function; may serve to automatically or substantiallyautomatically maintain a substantially motionless positioning of theultrasonic transducer(s) relative to the vessel of interest; and mayautomatically generate readings, outputs, and compare pre and postintervention values to measure changes.

FIG. 21A and FIG. 21B are “heat map” plots of the ultrasonic signalsgenerated by the matchstick transducers, according to some embodiments.FIG. 21A is illustrative of the signal generated in the XZ plane, withthe darkness indicative of signal strength. FIG. 21B is illustrative ofthe signal generated in the YZ plane. As indicated in FIG. 21B, the beamis generated at about 45 degree angle in the YZ plane, and the beam is“wedge”/conical shaped. A conical shape, for example, may include anoval cone, and in some embodiments, may be frusto-conical.

FIG. 21C is a more detailed version of FIG. 20B, showing the beam“wedge” in greater detail. In FIG. 21C, the relative signal strength isshown at 3 MHz for a matchstick transducer having the dimensions of 10×1mm, spaced at 3 mm.

FIG. 22 illustrates two matchstick elements and a blood vessel ofinterest, according to some embodiments. In this example, a firstmatchstick element 2202 provides a signal transmit function whereby theultrasound signal is generated in a wedge shape towards the blood vessel2206, for example, along center axis 2208. A second matchstick element2204 is configured to receive the signal that is reflected from bloodvessel 2206. The orientation is important in some embodiments, the firstmatchstick element 2202 is positioned in front of the second matchstickelement 2204 such that the signal emanating from first matchstickelement 2202 is not inadvertently impeded by the second matchstickelement 2204. Accordingly, in some embodiments, there may be somedirectionality related to the positioning of the device for properfunctioning (while the device provides a wide latitude of redundantangles and positioning, to get a sufficiently strong signal reading, thedevice may need to be oriented at least roughly in the correctdirection). Accordingly, there may be a rough “up” and “down’ directionassociated with the device, but the configuration of the matchsticktransducers and additional elements allow for a wide range of variationin orientations and positioning.

FIG. 23 illustrates a series of matchstick transducer pairs, accordingto some embodiments. In FIG. 23, the plurality of matchstick transducerpairs 2302, 2304, 2306, and 2308, in combination/in concert, provide an“unfocused curtain” 2310 of signal, all at or around the same anglerelative to the matchstick transducer pairs 2302, 2304, 2306, and 2308.While there may be some slight differences in angles between each of thetransducer pairs 2302, 2304, 2306, and 2308, for example, due to thedevice flexing to conform to the anatomy of an individual (e.g., if thespacing between the transducer pairs 2302, 2304, 2306, and 2308 is aflexible material), the angles are fairly constant and are not used tofocus the beams together.

Rather, the unfocused curtain 2310 of signal formed by the substantiallyconical/frusto-conical (e.g., “wedge” shaped) signals generated causes aplurality of different reflections and signals to be received by thereceiving transducers of each of the transducer pairs transducer pairs2302, 2304, 2306, and 2308. The receiving members of the transducerpairs, in some embodiments, do not discriminate between signals of thetransmitting transducer members, and accordingly, an improved signalstrength (and/or improved signal to noise ratio) is possible.

The unfocused curtain 2310 generated by the plurality of transducermembers generating signals increases the breadth of different angles ofplacement that still render a sufficiently strong received signalindicative of blood flow. For example, for a device that is haphazardlyplaced on an injured person in an emergency situation, reflections maybe identified at differing angles from each of the transducer signaltransmitting members, each having different strengths. Each of thesignal receiver members may receive signals of different amplitudes andfrequencies that may be indicative of blood flow across the vessel ofinterest, and in some embodiments, the device is configured to selectand process signals from a subset of signal receiver members (e.g., onlythose signal receiver members receiving the strongest signals).Accordingly, the device has increased flexibility in placement, andthere is no need for accurate landmarking of anatomical elements orcareful positioning or placement as the unfocused curtain 2310 increasesthe probability that at least one of the “wedges” is able to intersectthe blood vessel such that a sufficiently strong signal can be receivedby one of the signal receiver members.

FIG. 24 is a perspective rendering of a device, according to someembodiments. The device shown in FIG. 24 is shown as a non-limitingexample of a physical device, and includes a set of piezo-electriccrystal transducer pairs encased in an injection molded crystal retainerhousing. Each pair may have its own housing, and in this example, eachretainer housing is provided on a flexible circuit (e.g., for providingelectrical connectivity between the pairs), that is coupled to an energystorage device (e.g., a battery, a capacitor).

The flexible circuit may be disposed on a printed circuit board 2402,which is then provided within an injection molded rigid chassis 2406.Flexible urethane pads may be used to provide comfortable coupling whenpressed against the skin of a user, and the entirety of the device maybe housed within a silicon over-mold 2408 that is shaped as an adhesivebandage 240 having a hydrogel insert to aid in the dispersion of signalinto the body. The device may ultimately be placed on a backing paper2412 having an adhesive for application onto the body. The device mayinclude on-board processors and memory, which receive and process Ipre-process the signals received by the receiving elements of thetransducers.

These signals may be transmitted to downstream components for furtherprocessing, which in some embodiments, are remote from the device (e.g.,a smartphone, a computer, a tablet). In other embodiments, an on-boarddisplay or interface elements are disposed on or within the housing suchthat various alarms and notifications may be generated based on theprocessed signals. For example, the alarms and notifications mayindicate a quality of treatment and indicate to an emergency responderwhether treatment is effective or is failing, based on determinationsobtained from the processing signals, such as determined HRNTI ratios,among others.

FIG. 25 is an illustration indicating an approach to obtainingmeasurements and signals using a typical prior art handheld device. InFIG. 25, it is important to note that the required angle 2502necessarily needs to be very precise, otherwise a sufficient measurementis not obtained.

In FIGS. 26 and 27, a device providing an unfocused curtain 2310 isprovided, according to some embodiments. The device does not need to beprecisely positioned on the user, and the plurality of matchstick pairsof transducer elements allow for a plurality of partially overlapping“wedge shaped” signals to be transmitted, the angles being generallyconsistent except for differing angles due to the bandage conforming tothe form of the neck of the user. Accordingly, the probability of thedevice obtaining sufficiently strong signals in return is significantlyincreased relative to the device of FIG. 25, allowing for a redundancyof placement options and orientations.

The “unfocused” aspect of the curtain of ultrasound signal improves theusefulness of the example device of FIGS. 26 and 27 relative to thedevice of FIG. 25 in emergency situations. An unskilled or relativelyless skilled user would more readily be able to use the device toachieve a desired healthcare outcome of obtaining measurements andinsights based on blood flow characteristics of blood flow through thevessel of interest. In FIG. 27, while the signals of one of the pairs oftransducers on the device intersect the blood vessel at a 60 degreeangle, the other pairs may generate signals that intersect the bloodvessel at different angles (e.g., 50 degrees, 45 degrees, 65 degrees, 70degrees), and the receiving elements obtain an improved signal. In someembodiments, the transmit and receiving elements are individuallycontrollable such that the device is further configured to select asubset of receiving elements that have signals greater than a particularthreshold (or to simply pick the highest signal or the cleanest signal)

FIG. 28 is a photograph of a set of matchstick transducers, according tosome embodiments. The transducers are shown as examples, and variationsare possible. In the photographed example, the geometries of thetransducers are 1 mm×1 mm×10 mm in a four pair set oriented tip to tail.

The transducers, in combination, to create a long and flexibletransducer that produces signals in a saw tooth orientation (e.g.,similar to a matchstick on edge). Transducers can be embedded in aflexible housing to enable the transducer to flex and effectively coupleto the skin.

In a non-limiting example of a method of use, the orientation of thetransducer is placed across the neck (parallel to collar bone) and in adirection perpendicular to the orientation of the carotid. Positioningthe transducers in this orientation is found to increase the probabilityof intersecting the carotid and jugular, without the need forlandmarking or focusing ultrasound beams on the carotid, as required inconventional approaches.

The device may be of various shapes, dimensions, and sizes, and in apreferred embodiment, a length of device is about 45 mm, and thetransducer elements (e.g., transmitting elements) are spaced apart fromone another, while having generally the same angle (that may shiftslightly as the device conforms to a patient's body part).

Tight spacing is a consideration in relation to near fieldsensitivity—the spacing between elements provides for overlap betweenthe transmission and receiving signal fields. In various embodiments,the spacing of individual transmitting element to other transmittingelements is less than about 1 mm, less than about 2 mm, less than about3 mm, or less than about 4 mm, and the spacing should be less than orequal to 5 mm. depending on the frequency of operation.

In an illustrative example, the geometry of an array may include thefollowing: element (10 mm)-gap (1.5 mm)-element (10 mm)-gap (1.5mm)-element, etc. Similarly, the spacing of a transmitting array to areceiving array is less than about 1 mm, less than about 2 mm, less thanabout 3 mm, or less than about 4 mm, and the spacing should be less than5 mm.

Since the range to near field targets is fairly small (10-20 mm), theattenuation of the Doppler signal will be also quite low, and someattenuation of the Rx signal may be permissible due to non-overlap withthe Tx beam (Round Trip sensitivity loss at near field depths). Forexample, a reduction in near field Rx sensitivity due to non-overlap of20 dB may be acceptable, in some cases. In other words, the receivingsignal could be 20 dB weaker than an optimally aligned near fieldgeometry, and the device of some embodiments would still be operable.

Impedances can be selected to modify performance characteristics of thedevice. In experimentation, Applicants were able to obtain sufficientpenetration with a 40 ohm real part impedance and single endedtransmission driver.

In other embodiments, the device is adapted to increase the driveamplitude by a multiple of 2 by using a differential driverarchitecture, implying that the device is able to achieve goodperformance for impedances at high as 80 ohms real part impedance, forthe full transmitter array, all elements oriented in an electricalparallel connection.

In some embodiments, the transducers are selected to have an impedancespecification of between 30 ohms and 100 ohms real part. In someembodiments, the system includes a series tuning inductor configured totune out the series capacitance.

With respect to the receiver elements, the receiver elements are driveninto a high load impedance (>=1K ohm), so the element impedance isrelatively immaterial, and accordingly, receiver source impedance <about200 ohms may be appropriate, in some embodiments.

Alternatively, low impedance elements, with source impedances of <50ohms, can be terminated at the receiver input by a low impedancereceiver input impedance of <10 ohms. This alternative receivertermination can be used if it proves advantageous for optimum receivernoise performance.

A working depth of about 1-6 cm is provided, according to someembodiments. At the shallow depth, the attenuation of the Doppler signalwill be very low, and in some embodiments, a poor overlap of Tx and Rxbeams can be thus tolerated. For example, a 20 dB reduction in roundtrip sensitivity from targets on the nominal “center” of the beam couldbe allowable without significant impact of the Doppler performance.

In another embodiment, the device is skewed for improved sensitivity inthe 3-6 cm depth range, and with a tradeoff in performance in the nearfield.

In Applicants' experiments, in the lateral dimension (45 mm nominal) thebeam was found to have a basically rectangular shape, providingessentially a sheet of ultrasound energy. In an elevation dimension (1mm nominal), the beam was found to have some focusing, with a beamwidthof 20-30 degrees, allowing the thickness of the “sheet” of ultrasoundenergy to be set.

In a situation where the device is used to interrogate the target vesselat an angle of 45 degrees nominal, a −3 dB total beamwidth of 20 degreesmay cause some variance in the Doppler velocity, potentially in therange of +/−15%. For a 30 degree beamwidth, the Doppler velocityvariance will be about +/−20%, and Applicants' testing have indicatedthat a beamwidth of <30 degrees @−3 dB may be required for someembodiments.

In selecting operative frequencies, Applicants have identified thatabout 3-8 MHz frequency is operable, and 4-5 MHz is preferred.Experimental approaches have indicated that the signal is sufficientthat the transducer pairs can be wired in parallel, and FIG. 29 isprovided as an illustrative graph of blood signal level as compared todepth, according to some embodiments.

In some situations, there may be requirements to obtain deep tissuereadings (e.g., >4 cm about below the surface) as many critically illpatients have very large necks due to high body mass index. For example,where deep tissue readings are required, the dimensions and geometry ofthe device and/or transducers are modified to enable a deeper ultrasoundcurtain (e.g., for bariatric patients that are greater than 500 lbs).FIG. 30 is a graph illustrating received signal input level, in blood,showing dBvolts plotted against depth, in centimeters.

FIG. 31 shows further detail of a set of transducers in an ultrasoundbandage in accordance with one embodiment of the disclosed technology.Here, a number of transducer elements 3100, 3102, 3104 are electricallyconnected in parallel within the ultrasound bandage. As described above,one set of transducer elements is used for transmit and the other set isused for receive. In one embodiment, the transducers continually operatein a CW transmit/receive mode. However, pulsed modes could be used ifdesired. In the embodiment shown, the transducer elements 3100, 3102,3104 are rectangular pieces of PZT having a height (when viewed lookingat the front face) of approximately 1.2 mm. a length of approximately 12mm, and a thickness of approximately 0.5 mm. As will be appreciated, thedimensions of the transducer elements affect the beam pattern producedat the desired operating frequency of the transducer. In the embodimentshown, the transducer elements are sized to operate at approximately 4MHz and produce an unfocused beam pattern that spreads at about 20degrees in a generally conical manner from the front face of thetransducer. The number of connected transducer elements is dependent onthe desired size of the ultrasound bandage. In one embodiment, thereceive transducer elements are the same size as the transmit elementsand are spaced at approximately 0.5 cm in the lateral direction awayfrom the transmit elements and are oriented at the same angle e.g. 45degrees vertical. Although three transducer elements are shown, oneembodiment of the disclosed technology uses four transducer elementsthat are connected in parallel for transmit and four transducer elementsthat are connected in parallel for receive in order to provide asufficiently wide transmit and receive area. The wide transmit/receivearea allows the device to receive echo signals from a target vessel(common carotid or femoral artery etc.) despite slight variations inwhere or how the ultrasound bandage is placed on the patient. To createthe sheets of ultrasound energy beamed into the patient, the width (whenviewed from the front face) of the transducer elements is at least 8 andpreferably 10 times the height of the transducer element.

In one embodiment, the rear surface of the transducer elements 3100,3102, 3104 are connected by a common conductor such as a piece of copperfoil 3110 that is bonded to the PZT with a conductive epoxy. A similarcommon conductor 3112 is bonded to the front face of the transducerelements. The common conductors 3110, 3112 are connected to a shieldedelectrical conductor such a co-axial cable 3120 that either provides theultrasound driving signals to the transmit elements or carries signalsfrom the receive elements that are produced in response to detected echosignals.

Backing material 3124 may be secured over the conductor 3110 on the rearof the transducer elements to help reduce transmission losses. Thebacking material 3124 may be individual segments that are connected toeach transducer element or a continuous piece or layer that is securedto the rear surface of all the transducer elements.

In some embodiments, a matching layer (not shown) such a powder filledepoxy may be placed on the front surface of the transducer if theimpedance of the transducer is not sufficiently matched to a gel layeror other intermediate layer that lies between the transducer and theskin of the patient. In the embodiment shown, the beam pattern from thetransducer elements flare out at approximately 20 degrees from normal tothe transducer front face. When oriented in an ultrasound patch at anangle of 45 degrees to the surface of the skin, ultrasound istransmitted and received over a range of approximately 25-65 degreeswith respect to the plane of the skin surface.

FIG. 32 is a block diagram of the signal processing components withinthe ultrasound patch in accordance with one embodiment of the disclosedtechnology. Controlling the overall function of the ultrasound bandageis a microcontroller 3202 or microprocessor. The microcontroller mayinclude its own memory for storing instructions and data. Alternatively,the microcontroller may interface with external memory (not shown) thatis used to store the instructions and data.

In the transmit signal path, a clock generator 3204 generates a 16 MHzclock signal for the microcontroller 3202. The 16 MHz signal is divideddown to 4 MHz to generate the ultrasound transmit signals. The 4 MHzsignal from the clock generator 3204 is provided to a transmit drivercircuit 3206 that is configured to provide a 4 MHz/3.7 Volt peak to peaksquare wave from the 4 MHz input signal. In one embodiment, the outputof the transmit driver 3206 is connected to the transducer elementsthrough a number of series connected resistors. Each resistor isconnected in parallel to a transistor switch that is controlled by themicrocontroller 3202. By turning on a bypass transistor, the connectedresistor is effectively removed from the series circuit so that thedriving signal produced by the transmit driver circuit 3206 can beselectively attenuated under the control of the microcontroller 3202. Inone embodiment, the series resistors provide up to 15 dB of attenuation.Depending on the number and value of the series connected resistors, theattenuation may be controlled in a number of equal or unequal steps. Thedriving signals (attenuated or not) from the transmit driver circuit3206 are applied in parallel to the transducer elements 3208 as shown inFIG. 31.

In the receive path, the signals from the parallel connected set ofreceiving transducer elements 3220 are connected to a transistor preamp3222 that is configured to provide 22 dB of gain. The transistor preamp3222 should be low noise and in one embodiment has a relatively lowinput impedance of about 3 ohms. Because the transmit and receive pathsare separate in one embodiment of the disclosed technology, notransmit/receive switch is necessary. However, if the same transducerelements are used for both transmit and receive in a pulsed ultrasoundsystem, then a transmit/receive switch controlled by either the transmitdriver 3206 or the microcontroller 3202 could be used. Signals from thetransistor preamp 3222 are supplied to an integrated circuit operationalamplifier circuit 3224 that is configured to provide 14 dB of gain witha 1 k-ohm input impedance. After increasing the gain of the receivedultrasound signals, the signals are applied to quadrature demodulator3226 that mixes the signals to baseband by multiplying them with two 4MHz signals that are 90 degrees out of phase. The result is two signalsthat are shown as base band I (BB_I) and base band Q (BB_Q). The BB_Iand BB_Q signals are in the audio frequency range and contain bothamplitude and Doppler shift information.

The BB_I and BB_Q are then filtered in two different filter paths, onefor each signal. Each channel is the same so that only the filters inone path are described. The signals are first subjected to a low passfilter 3230 a having a single pole at 20 KHz to remove any frequencycomponents substantially above the cut off frequency. The remaining lowfrequency signals are then filtered by an active high pass filter 3232 ahaving a double pole at 100 Hz and that provides 42 dB of gain in oneembodiment. The output of the low pass filter 3232 a is supplied to avariable attenuation control 3234 a that can provide up to 15 dB ofattenuation. The variable attenuation control 3234 a can be implementedin a number of ways including a number of serially connected resistorsthat are bypassed by transistor switches as described above. Thetransistor switches are activated by signals from the microcontroller3202 in order to put the resistors in series or to bypass them.

Following the selective attenuation control, the signals are applied toa second active low pass filter having 2 poles at 7 KHz and thatprovides 30 dB of gain to substantially remove any signal componentsabove the cut off frequency. Finally, the BB_I and BB_Q signals areapplied to a pair of all-pass filters 3228 a, 3238 b that pass allfrequencies and operate to put a 90 degree phase rotational shiftbetween the two signals. This phase rotation is required for subsequentseparation of the Forward and Reverse Flow signals, corresponding to theforward and reverse blood flow in the vessel being interrogated. Theoutput of the all pass filters 3228 a, 3228 b are the I and Q signalsthat contain both the amplitude and Doppler information of the echosignals returning from the isonified vessel. The I and Q signals areapplied to a flow converter circuit 3240 that in one embodiment is alogic circuit configured to add the I and Q signals in order to producea signal (FWD) that is proportional to the forward Doppler signal and tosubtract the I and Q signals to produce a signal (REV) that isproportional to the reverse Doppler signal. In addition, the flowconverter 3240 includes an amplifier to add 6 dB of gain.

As will be appreciated, the signal processing shown in FIG. 32 isperformed in analog primarily as a mechanism to keep component cost low.However, it will be appreciated that the I and Q signals from thereceived ultrasound signals could also be determined digitally with asuitable microprocessor or DSP and an analog to digital converter.

FIG. 33 shows one embodiment of some outputs that provide visual and/oraural information to the user of the flow through the vessel beinganalyzed. In the embodiment shown, the FWD signal that is representativeof the forward Doppler shift in the returning ultrasound echo signals isprovided both visually and/or aurally to the operator. In other casesthe REV signal proportional to the reverse Doppler shift could be used.However, this signal typically is less strong. In the embodiment shown,the FWD signal is applied to a frequency to voltage converter 3302. Thefrequency to voltage converter 3302 produces an analog voltage signalthat changes with changes in the mean frequency of the received echosignals. The analog voltage signal from the frequency to voltageconverter 3302 is digitized by an analog to digital converter 3304 thatmay be included in the microcontroller 3202 described above.

A representation of the digitized FWD signal is displayed to theoperator on a bar-graph of LEDs or other visual display that is on thecase of the ultrasound bandage. In some embodiments, the LEDs may becalibrated based on known flow rates to give the operator moreinformation about the blood flowing in the vessel being analyzed.Because the analog voltage produced by the frequency to voltageconverter 3302 is composed of relatively low frequency signals, theanalog to digital converter 3304 can operate at a slow sampling ratesuch as 50 samples/sec. A speaker driver circuit 3310 converts theapplied FWD or REV Doppler signal into an audio signal that can drive anaudio speaker. In one embodiment, the speaker driver is a push-pulltransistor design that produces a 7 Volt peak to peak signal that issufficient to drive a piezoelectric speaker mounted into a case of theultrasound bandage. The resulting audio is the well-known Doppler bloodflow whooshing sound that is familiar to physicians. The FWD or REVDoppler signal can also be applied to an audio jack 3318 to allow anexternal speaker and driver circuit to be plugged into the ultrasoundbandage with a conventional audio cable. Other user interfaces couldalso be used such as multi-color LED's where the color of the LEDindicates flow (e.g. green forward flow, red no forward flow etc.).

As indicated above, attenuation controls are provided to adjust one orboth of the transmit power of the ultrasound signals delivered to thepatient and the amount of grain applied to the received echo signals. Aninput such a button (not shown) on the case of the ultrasound bandageallows an operator to provide signals to the microcontroller to adjustone or both of these parameters so that the Doppler signals are strongenough to that they can be seen and heard but not so strong that thevisual/aural outputs on the ultrasound bandage are saturated. In otherembodiments, the attenuation of the transmit and received signals can becontrolled under the direction of software executed by themicrocontroller such that the detected Doppler signals fall in thedesired operating range.

Additional information can also be provided by the ultrasound bandagethat is based on an analysis of the detected Doppler signals. In oneembodiment, the selected FWD or REV Doppler signal is digitized by afaster analog to digital converter 3320 that samples the signals at arate of, for example, 15 K samples/sec. The digitized Doppler signalsare then analyzed by the microcontroller to determine such quantities asthe patient's VTI at a time that is before and after a physical test(e.g. leg raise, chest compressions, defibrillation, ventilation etc.)

Measured qualities of the analyzed Doppler signals can be sent to aremote device through a wired or wireless link using an interface 3330such as Bluetooth, 802.15 or an infrared link or a wired link such asUSB connection that connects the ultrasound bandage may connect toexternal equipment (patient monitor, defibrillator, mechanicalventilator etc.). In some embodiments, measured qualities of thedetected flow are stored in a memory accessed by the microcontrolleruntil such time as the ultrasound bandage is connected to an externalreader.

FIGS. 34A-44 illustrate the construction of a ultrasound bandage inaccordance with one embodiment of the disclosed technology. FIG. 34Ashows a cross section of a pair of ultrasound transducer elements 3410,3412. As indicated above, in one embodiment, the transducers have aheight of 1.2 cm on a front face of the transducers and a thickness of1.00 cm. The transmit and receive transducers are spaced laterally by adistance of 0.5 cm. However the sizes and spacing of the transducerelements may be adjusted depending on the depth of tissue to be imaged,the operating frequency of the transducers etc. For example ultrasoundbandages for pediatric use may employ smaller transducers. Conversely,ultrasound bandages for large patients or for veterinary use may employlarger transducers.

As shown in FIG. 35A, the transmit and receive transducers are potted ina block 3502 of a backing material. In the embodiment shown, each block3502 contains one transmit and one receive transducer. However, a singleblock could contain more than one transmit/receive pair of transducerelements.

As shown in FIG. 36, a number of blocks of backing material are mountedto a flex circuit 3602 that contains traces to route signals to and fromthe transducer elements. In one embodiment, connections between the flexcircuits and the metal electrodes on the transducer elements can be madewith jumper wires. Alternatively, the metal electrodes on the faces ofthe transducers can be fashioned to include a tab or other electricalconnection that extends through the rear surface of the block of backingmaterial 3502 that connect to a contact pad on the flex circuit with aconductive adhesive or solder connection.

As shown in FIG. 37, a battery 3702 is fitted behind the flex circuit3602 to provide power to the components in the ultrasound bandage. Thebattery is preferably lithium polymer battery but other batterychemistries could be used. In one embodiment, the battery is designed tobe used once. However, the battery could also be a rechargeable typeprovided that the ultrasound bandage can be properly cleaned.

FIG. 38 shows the flex circuit 3602 connected to a printed circuit board3802 that holds the components shown in the block diagrams of FIGS. 32and 33. A chassis 3902 is placed over the battery and circuit board withthe flex circuit extending through a hole in the chassis so that thetransducers can be seated on an outer surface of the chassis as shown inFIG. 39. In one embodiment, one or more polyurethane pads 4002 arepositioned between the back surface of the flex circuit and the uppersurface of the chassis to allow the transducers to be compressed whenthe ultrasound bandage is placed on the patient and to provide someamount of “float” for the transducer elements so they are not rigidlyconnected to the printed circuit board as shown in FIG. 40.

As shown in FIG. 41 a silicone over mold 4102 is placed over the chassisand the circuit board. The over mold 4102 has a hole over thetransducers so as not to interfere with the transmission and receptionof ultrasound signals. The over mold 4102 preferably includes one ormore holes in the area of the LEDs and speaker so as not to interferewith their operation. If water or liquid ingress is likely, then theover mold may completely seal in the printed circuit board.

An adhesive pad 4202 is placed around the perimeter of the silicone overmold on the bottom surface of the ultrasound bandage so that the bandagecan be adhered to the skin of a patient as shown in FIG. 42. Theadhesive pad 4202 surrounds the perimeter of the over mold 4102 and hasan open area in front of the transducer elements.

As shown in FIG. 43, the opening in the silicone over mold in the areain front of the transducer elements is filled with a hydrogel insert4302 or other suitable acoustic coupling medium to ensure a goodacoustic connection between the ultrasound bandage and the patient'sskin. A non-stick covering (not shown) is placed over the hydrogelinsert 4302 and the adhesive pad so that the unit remains sterile (orsuitably clean) before use and the adhesive remains tacky. During use,the non-stick covering is removed to expose the adhesive and thehydrogel before the unit is placed on a patient.

FIG. 44 shows a top view of the ultrasound bandage with some componentson the printed circuit board visible through the silicone over mold.

As shown in FIG. 44, a plastic shell is placed over the printed circuitboard on the top of the ultrasound bandage. The plastic shell has one ormore ports to allow the ultrasound bandage to be connected an externalspeaker or other medical device. In addition, the shell 4502 includesone or more user controls such as buttons, touch sensors or the likewith which a user can change the settings of the ultrasound bandage toperform such tasks as powering the unit on or off and adjusting thetransmit and receive powers. Although not shown in FIG. 44, the casealso includes the visual display (e.g. LEDs or the like) and holes for aspeaker so that a user can hear the Doppler signals detected.

As described above, the disclosed technology is useful for assessing thevascular flow of a patient and in particular to measure any differencesin flow when some sort of procedure or test is performed on the patient.The ultrasound bandage can capture measurements of flow before the testor procedure (to use as a baseline) and compare them with flow detectedafter the procedure or test is performed. In one embodiment, themicrocontroller of the ultrasound bandage is programmed to communicatewith an external medical device and to take measurements and transmitthem when instructed by the medical device. As indicated above, such acommunication connection can be made by a wireless (e.g. Bluetooth andthe like) or a wired (e.g. USB) connection.

In some embodiments, the microcontroller is programmed to provideinstructions to the user such as “Prepare for leg raise test” It isprogrammed to measure and store a Doppler measurement before the testand again after an instruction is given to ask the operator to performthe test. A visual or auditory signal can be given informing theoperator of the detected flow. In addition, the microcontroller can beprogrammed to provide audio instructions to the operator through thespeaker to trigger the test sequence.

In some embodiments, the ultrasound bandage is configured to pair withother medical equipment such as defibrillators, ventilators etc. Theconnected medical device instructs the ultrasound bandage to performperiodic flow measurements and report the results, which may be used toalter treatment given or recommended by the connected medical device. Asindicated above, such a pairing can be made with a wired or wirelessconnection.

In other embodiments, the ultrasound bandage is configured to pair withconsumer electronics such as a smart phone. The ultrasound bandage canbe instructed by the electronics to perform flow measurements andtransmit the results to the connected consumer electronics.

The following is an example of how a before and after evaluation ofvessel flow can determined with the ultrasound bandage of the presenttechnology.

End Expiratory Occlusion Test is a clinical maneuver employed todetermine if a patient is fluid (volume) responsive. The maneuver relieson cyclical changes in intra-thoracic pressure as a consequence ofventilator-delivered breaths; thus it may be performed only in patientsreceiving mechanical ventilation. When a patient is volume responsive,an increase in intra-thoracic pressure [i.e. during a ventilatorinspiration] transiently reduces left ventricular outflow while adecrease in intra-thoracic pressure [i.e. during a ventilatorexpiration] results in a transient augmentation of left ventricularoutflow. When a patient is not volume responsive, these cyclical changesin intra-thoracic pressure do not cause appreciable changes in leftventricular output.

The end-expiratory occlusion test [i.e. EEOT] measures the transientaugmentation of left ventricular output following a prolonged [at least15 second] prolongation of end-expiration, especially the final 5seconds. The end-inspiratory occlusion test [i.e. EIOT] measures thetransient fall in left ventricular output follow a prolongation ofend-inspiration on the ventilator—especially the terminal 5 seconds ofthe hold. Measuring the augmentation of left ventricular output during aprolonged end-expiratory hold [i.e. the EEOT] has been done viapulse-contour measured cardiac output as well as aortic andtransthoracic measured augmentation of velocity time-integral. The testis considered positive if the sum of the decrement in end-inspiratoryVTI and augmentation of end-expiratory VTI is at least 13%.

The EEOT and end-inspiratory occlusion tests have not been performedusing change in carotid VTI, however, it is expected that the physiologywill be similar and therefore will have comparable VTI thresholds. Basedon changes in carotid VTI in response to passive leg raise it isexpected that the difference in carotid VTI will be close to 20%following EIOT and EEOT. As noted, the EEOT and EIOT are probably onlyappropriate cardiovascular stresses for pulse-contour-derived cardiacmeasurements and VTI. For the EEOT test, the technique must be able todetect small changes in cardiac output. This might not be the case forthe current version of bioreactance device, which averages cardiacoutput values on a too long time for being able to detect changesoccurring in laps of a few seconds.

In one embodiment of the disclosed technology, a ventilator protocol isdefined while monitoring the effect of the EEOT & EIOT on carotid flowto identify if a patient is not safe for liberation from mechanicalventilation. The carotid flow is measured by with the ultrasound bandagedescribed above.

While not-yet tested using EEOT & EIOT, a patient who is not volumeresponsive following a passive leg raise—deemed ‘preloadindependent’—has been shown to be at high risk for failure to liberate(e.g. remove) from mechanical ventilation. The following algorithm is tobe implemented when using an EEOT/EIOT in conjunction with DopplerUltrasound VTI monitoring. The algorithm may be integrated intopre-existing liberation algorithms utilized by mechanical ventilators.These algorithms, however, focus only on pulmonary mechanics andgas-exchange; they do not incorporate as assessment of cardiovascularload when estimating safety for liberation from mechanical ventilation.

A patient is deemed clinically appropriate for consideration forliberation from mechanical ventilation [e.g. diseasecourse/critical-illness resolving, awake, protecting airway, clearingsecretions]. Step 1: The ventilator begins its automated assessment ofrespiratory mechanics, gas exchange, respiratory load [e.g. oxygensaturation, level of PEEP, rapid-shallow-breathing-index, etc.]. Thesealgorithms tend to be proprietary

Step 2: If the patient fails the aforementioned algorithm, theventilator performs an automated end-inspiratory occlusion test [i.e.EIOT] and receives input from the ultrasound bandage—measuring the fallin carotid VTI in the terminal 5 seconds of the end-inspiratory hold.One minute is allowed to pass to allow for cardiac output to return tobaseline. The ventilator then applies a 15 second end-expiratory holdand measures the rise in carotid VTI from the ultrasound bandage duringthe terminal 5 seconds of the EEOT. If the fall in carotid VTI duringthe end of the EIOT added to the rise in the carotid VTI during the endof the EEOT are below a predetermined threshold—that is, the patient isdeemed ‘preload independent’ the ventilator should alert the clinicianthat cardiac load is high and consideration for optimization of cardiacfilling pressures should be performed prior to liberation frommechanical ventilation [e.g. blood pressure control, volume control withdiuretics, etc.].

If the patient passes step 2, the ventilator will perform the approachin step 3 as well. If the patient is found to be preload ‘dependent’then liberation from mechanical ventilation is recommended. If thepatient fails, again, optimization of cardiac loading conditions shouldbe implemented.

The embodiments of the devices, systems and methods described herein maybe implemented in a combination of both hardware and software. Theseembodiments may be implemented on programmable computers, each computerincluding at least one processor, a data storage system (includingvolatile memory or non-volatile memory or other data storage elements ora combination thereof), and at least one communication interface.

Program code is applied to input data to perform the functions describedherein and to generate output information. The output information isapplied to one or more sensory output devices. In some embodiments, thecommunication interface may be a network communication interface. Inembodiments in which elements may be combined, the communicationinterface may be a software communication interface, such as those forinter-process communication. In still other embodiments, there may be acombination of communication interfaces implemented as hardware,software, and combination thereof.

Throughout the foregoing discussion, numerous references is be maderegarding servers, services, interfaces, platforms, or other systemsformed from computing devices.

It should be appreciated that the use of such terms is deemed torepresent one or more computing devices having at least one processorconfigured to execute software instructions stored on a computerreadable tangible, non-transitory medium. For example, a server caninclude one or more computers operating as a web server, databaseserver, or other type of computer server in a manner to fulfilldescribed roles, responsibilities, or functions.

The embodiments described herein are also implemented by physicalhardware, including computing devices, servers, receivers, transmitters,processors, memory, displays, and networks. The embodiments describedherein provide useful physical machines and particularly configuredcomputer hardware arrangements.

The embodiments described herein are also directed to electronicmachines and methods implemented by electronic machines adapted forprocessing and transforming ultrasonic signals which represent varioustypes of information. The embodiments described herein pervasively andintegrally relate to machines, and their uses; and the embodimentsdescribed herein have no meaning or practical applicability outsidetheir use with computer hardware, machines, and various hardwarecomponents.

Substituting the physical hardware particularly configured to implementvarious acts for non-physical hardware, using mental steps for example,may substantially affect the way the embodiments work. Such hardwarelimitations are clearly essential elements of the embodiments describedherein, and they cannot be omitted or substituted for mental meanswithout having a material effect on the operation and structure of theembodiments described herein. The hardware is essential to implement thevarious embodiments described herein and is not merely used to performsteps expeditiously and in an efficient manner. In some embodiments, thedevice is a single or special purpose machine that is specificallydesigned to perform limited set of functionality.

Although the embodiments have been described in detail, it should beunderstood that various changes, substitutions and alterations can bemade herein.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized.

As can be understood, the examples described above and illustrated areintended to be exemplary only.

What is claimed is:
 1. A device for detecting vascular flow, comprising:a case configured to be grasped by a user's hand and placed on a patientover first and second vessels which flow is to be detected, wherein thecase has a width and a length dimension; circuitry in the case includingtransmit and receive circuitry for transmitting ultrasound signals andprocessing corresponding received ultrasound echo signals, the circuitryfurther comprising processing circuitry configured to process thereceived ultrasound echo signals, the processing circuitry creating twochannels with directional signal content in response to receivingultrasound echo signals from the first vessel having flow in a firstdirection and from the second vessel having flow in a second directionthat is different than the first direction; a battery in the case forpowering the circuitry; and a number of pairs of transmit and receivetransducer elements that are fully contained in the case, whereinadjacent pairs of transmit and receive elements are axially alignedwithin the case in the direction of the length of the case and areelectrically connected to each other, each transmit and receivetransducer element having a height, a thickness and a width configuredto provide ultrasound signals with a selected operating frequency, theultrasound signals having a shaped, unfocused overlapping signal patternacross a range of depth of approximately 1-4 centimeters, the pairs oftransmit and receive transducer elements being oriented to transmit andreceive the ultrasound signals at an angle that is acute to a plane of abottom surface of the device; wherein the transmit and receive circuitryis configured to cause the transmit and receive element pairs tosimultaneously transmit and receive the ultrasound signals to produceecho signals representative of flow in at least one of the first andsecond vessels.
 2. The device of claim 1, wherein each transmit andreceive transducer element is a generally rectangular piece ofpiezoelectric material, wherein the width is at least 8 times the heightof the transducer element and wherein the pairs of transducer elementsare aligned such that their width dimensions extend along the length ofthe case.
 3. The device of claim 2, wherein the transmit and receivetransducer elements are oriented at approximately 45 degrees withrespect to the plane of the bottom surface of the device.
 4. The deviceof claim 3, further comprising circuitry in the case to measure aDoppler shift in the received ultrasound echo signals and circuitry inthe case for producing an indication of the measured Doppler shift to anoperator.
 5. The device of claim 4, wherein the circuitry furtherincludes a processor that is configured to execute programmedinstructions to: determine a Doppler shift in the received echo signalsprior to procedure being performed on the patient; determine a Dopplershift in the received echo signals after the procedure is performed onthe patient; and produce an indication of a difference in the Dopplersignals before and after the procedure is performed.
 6. The device ofclaim 5, wherein the circuitry includes communication circuitry toconnect the device to an external device; and wherein the processor isconfigured to execute instructions to transmit the difference in theDoppler signals before and after the procedure is performed to theexternal device.
 7. The device of claim 1, wherein the processingcircuitry includes A) a quadrature demodulator or B) a microprocessor ordigital signal processor and an analog to digital converter.
 8. A devicefor detecting vascular flow, comprising: a case configured to be graspedby a user's hand and placed on a patient over a vessel in which flow isto be detected, wherein the case has a width and a length dimension;transmit and receive circuitry in the case configured to transmitultrasound signals and to process received ultrasound echo signals; abattery in the case for powering the transmit and receive circuitry; anda number of pairs of transmit and receive transducer elements in thecase, each pair being secured in a mounting block that orients thetransmit and receive transducer elements at an acute angle with respectto a plane of a bottom surface of the device, wherein transmitting andreceiving surfaces of the transmit and receive transducer elements areconfigured to face away from the mounting block.
 9. The device of claim8, wherein adjacent mounting blocks are secured to a flexible printedcircuit so that the pairs of transmit and receive transducer elementsare flexible along the length of the case.
 10. The device of claim 8,wherein each transmit and receive transducer element is a generallyrectangular piece of piezoelectric material having a height, a thicknessand a length, wherein the length is at least eight times the height ofthe transducer element and wherein the pairs of transducer elements arealigned such that their length dimensions extend along the length of thecase.
 11. The device of claim 8, wherein the transmit and receivetransducer elements are oriented at approximately 45 degrees withrespect to a plane of the bottom surface of the device.
 12. The deviceof claim 8, further comprising processing circuitry in the case tomeasure a Doppler shift in the received ultrasound echo signals and forproducing an indication of the measured Doppler shift to an operator.13. The device of claim 8, wherein the device includes a processor inthe case that is configured to execute programmed instructions to:determine a Doppler shift in the received echo signals prior to aprocedure being performed on the patient; determine a Doppler shift inthe received echo signals after the procedure is performed on thepatient; and produce an indication of a difference in the Doppler shiftbefore and after the procedure is performed.
 14. The device of claim 13,wherein the device includes communication circuitry in the case toconnect the device to an external device; and wherein the processor isconfigured to execute instructions to transmit the difference in theDoppler shift before and after the procedure is performed to theexternal device with the communication circuitry.
 15. The device ofclaim 14, wherein the communication circuitry includes a wiredconnection.
 16. The device of claim 14, wherein the communicationcircuitry is for wireless communication.
 17. The device of claim 8,wherein the mounting block includes a pair of grooves in which thetransducer elements are secured and wherein the grooves are angled atdifferent acute angles with respect to the plane of the bottom surfaceof the device.
 18. A device for detecting flow in a vessel of a patient,comprising: a case configured to be removably attached to the patientover the vessel in which flow is to be detected; transmit and receivecircuitry in the case that is configured to transmit ultrasound signalsand to process received ultrasound echo signals; and a number of pairsof transmit and receive transducer elements in the case, each transducerelement comprising a sheet of piezoelectric material having a heightdimension, a length dimension and a thickness, wherein the lengthdimension is at least 8 times the height dimension and wherein thedevice includes two or more pairs of transmit and receive elements thatare aligned lengthwise in the case to transmit and receive ultrasoundsignals.
 19. The device of claim 18, wherein each of the transmit andreceive transducer elements comprises a conductive epoxy backing layer.20. The device of claim 18, wherein each of the transmit and receivetransducer elements comprises a conductive epoxy matching layer.